class QByteArray#

The QByteArray class provides an array of bytes. More…

Synopsis#

Methods#

def __init__()
def __getitem__()
def __len__()
def __mgetitem__()
def __msetitem__()
def __reduce__()
def __repr__()
def __setitem__()
def __str__()
def append()
def assign()
def at()
def back()
def capacity()
def cbegin()
def cend()
def chop()
def chopped()
def clear()
def compare()
def contains()
def count()
def data()
def endsWith()
def erase()
def fill()
def first()
def front()
def indexOf()
def insert()
def isEmpty()
def isLower()
def isNull()
def isSharedWith()
def isUpper()
def isValidUtf8()
def last()
def lastIndexOf()
def left()
def leftJustified()
def length()
def mid()
def __ne__()
def __add__()
def __iadd__()
def __lt__()
def __le__()
def __eq__()
def __gt__()
def __ge__()
def operator[]()
def percentDecoded()
def prepend()
def push_back()
def push_front()
def remove()
def removeAt()
def removeFirst()
def removeLast()
def repeated()
def replace()
def reserve()
def resize()
def right()
def rightJustified()
def setNum()
def setRawData()
def shrink_to_fit()
def simplified()
def size()
def sliced()
def split()
def squeeze()
def startsWith()
def swap()
def toBase64()
def toDouble()
def toFloat()
def toHex()
def toInt()
def toLong()
def toLongLong()
def toLower()
def toPercentEncoding()
def toShort()
def toStdString()
def toUInt()
def toULong()
def toULongLong()
def toUShort()
def toUpper()
def trimmed()
def truncate()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

QByteArray can be used to store both raw bytes (including ‘\0’s) and traditional 8-bit ‘\0’-terminated strings. Using QByteArray is much more convenient than using const char *. Behind the scenes, it always ensures that the data is followed by a ‘\0’ terminator, and uses implicit sharing (copy-on-write) to reduce memory usage and avoid needless copying of data.

In addition to QByteArray , Qt also provides the QString class to store string data. For most purposes, QString is the class you want to use. It understands its content as Unicode text (encoded using UTF-16) where QByteArray aims to avoid assumptions about the encoding or semantics of the bytes it stores (aside from a few legacy cases where it uses ASCII). Furthermore, QString is used throughout in the Qt API. The two main cases where QByteArray is appropriate are when you need to store raw binary data, and when memory conservation is critical (e.g., with Qt for Embedded Linux).

One way to initialize a QByteArray is simply to pass a const char * to its constructor. For example, the following code creates a byte array of size 5 containing the data “Hello”:

ba = QByteArray("Hello")

Although the size() is 5, the byte array also maintains an extra ‘\0’ byte at the end so that if a function is used that asks for a pointer to the underlying data (e.g. a call to data() ), the data pointed to is guaranteed to be ‘\0’-terminated.

QByteArray makes a deep copy of the const char * data, so you can modify it later without experiencing side effects. (If, for example for performance reasons, you don’t want to take a deep copy of the data, use fromRawData() instead.)

Another approach is to set the size of the array using resize() and to initialize the data byte by byte. QByteArray uses 0-based indexes, just like C++ arrays. To access the byte at a particular index position, you can use operator[](). On non-const byte arrays, operator[]() returns a reference to a byte that can be used on the left side of an assignment. For example:

ba = QByteArray()
ba.resize(5)
ba[0] = 0x3c
ba[1] = 0xb8
ba[2] = 0x64
ba[3] = 0x18
ba[4] = 0xca

For read-only access, an alternative syntax is to use at() :

for i in range(0, ba.size()):
    if ba.at(i) >= 'a' and ba.at(i) <= 'f':
        print("Found character in range [a-f]")

at() can be faster than operator[](), because it never causes a deep copy to occur.

To extract many bytes at a time, use first() , last() , or sliced() .

A QByteArray can embed ‘\0’ bytes. The size() function always returns the size of the whole array, including embedded ‘\0’ bytes, but excluding the terminating ‘\0’ added by QByteArray . For example:

ba1 = QByteArray("ca\0r\0t")
ba1.size() # Returns 2.
ba1.constData() # Returns "ca" with terminating \0.
ba2 = QByteArray("ca\0r\0t", 3)
ba2.size() # Returns 3.
ba2.constData() # Returns "ca\0" with terminating \0.
ba3 = QByteArray("ca\0r\0t", 4)
ba3.size() # Returns 4.
ba3.constData() # Returns "ca\0r" with terminating \0.
cart = {'c', 'a', '\0', 'r', '\0', 't'}
ba4 = QByteArray(QByteArray.fromRawData(cart, 6))
ba4.size() # Returns 6.
ba4.constData() # Returns "ca\0r\0t" without terminating \0.

If you want to obtain the length of the data up to and excluding the first ‘\0’ byte, call qstrlen() on the byte array.

After a call to resize() , newly allocated bytes have undefined values. To set all the bytes to a particular value, call fill() .

To obtain a pointer to the actual bytes, call data() or constData() . These functions return a pointer to the beginning of the data. The pointer is guaranteed to remain valid until a non-const function is called on the QByteArray . It is also guaranteed that the data ends with a ‘\0’ byte unless the QByteArray was created from raw data . This ‘\0’ byte is automatically provided by QByteArray and is not counted in size() .

QByteArray provides the following basic functions for modifying the byte data: append() , prepend() , insert() , replace() , and remove() . For example:

x = QByteArray("and")
x.prepend("rock ") # x == "rock and"
x.append(" roll") # x == "rock and roll"
x.replace(5, 3, "") # x == "rock  roll"

In the above example the replace() function’s first two arguments are the position from which to start replacing and the number of bytes that should be replaced.

When data-modifying functions increase the size of the array, they may lead to reallocation of memory for the QByteArray object. When this happens, QByteArray expands by more than it immediately needs so as to have space for further expansion without reallocation until the size of the array has greatly increased.

The insert() , remove() and, when replacing a sub-array with one of different size, replace() functions can be slow ( linear time ) for large arrays, because they require moving many bytes in the array by at least one position in memory.

If you are building a QByteArray gradually and know in advance approximately how many bytes the QByteArray will contain, you can call reserve() , asking QByteArray to preallocate a certain amount of memory. You can also call capacity() to find out how much memory the QByteArray actually has allocated.

Note that using non-const operators and functions can cause QByteArray to do a deep copy of the data, due to implicit sharing .

QByteArray provides STL-style iterators ( const_iterator and iterator ). In practice, iterators are handy when working with generic algorithms provided by the C++ standard library.

Note

Iterators and references to individual QByteArray elements are subject to stability issues. They are often invalidated when a QByteArray -modifying operation (e.g. insert() or remove() ) is called. When stability and iterator-like functionality is required, you should use indexes instead of iterators as they are not tied to QByteArray ‘s internal state and thus do not get invalidated.

Note

Iterators over a QByteArray , and references to individual bytes within one, cannot be relied on to remain valid when any non-const method of the QByteArray is called. Accessing such an iterator or reference after the call to a non-const method leads to undefined behavior. When stability for iterator-like functionality is required, you should use indexes instead of iterators as they are not tied to QByteArray ‘s internal state and thus do not get invalidated.

If you want to find all occurrences of a particular byte or sequence of bytes in a QByteArray , use indexOf() or lastIndexOf() . The former searches forward starting from a given index position, the latter searches backward. Both return the index position of the byte sequence if they find it; otherwise, they return -1. For example, here’s a typical loop that finds all occurrences of a particular string:

ba = QByteArray("We must be , very ")
j = 0
while (j = ba.indexOf("<b>", j)) != -1:
    print("Found <b> tag at index position ", j)
    j = j + 1

If you simply want to check whether a QByteArray contains a particular byte sequence, use contains() . If you want to find out how many times a particular byte sequence occurs in the byte array, use count(). If you want to replace all occurrences of a particular value with another, use one of the two-parameter replace() overloads.

QByteArray s can be compared using overloaded operators such as operator<(), operator<=(), operator==(), operator>=(), and so on. The comparison is based exclusively on the numeric values of the bytes and is very fast, but is not what a human would expect. localeAwareCompare() is a better choice for sorting user-interface strings.

For historical reasons, QByteArray distinguishes between a null byte array and an empty byte array. A null byte array is a byte array that is initialized using QByteArray ‘s default constructor or by passing (const char *)0 to the constructor. An empty byte array is any byte array with size 0. A null byte array is always empty, but an empty byte array isn’t necessarily null:

QByteArray().isNull() # returns true
QByteArray().isEmpty() # returns true
QByteArray("").isNull() # returns false
QByteArray("").isEmpty() # returns true
QByteArray("abc").isNull() # returns false
QByteArray("abc").isEmpty() # returns false

All functions except isNull() treat null byte arrays the same as empty byte arrays. For example, data() returns a valid pointer (not nullptr) to a ‘\0’ byte for a null byte array and QByteArray() compares equal to QByteArray (“”). We recommend that you always use isEmpty() and avoid isNull() .

Maximum size and out-of-memory conditions#

The maximum size of QByteArray depends on the architecture. Most 64-bit systems can allocate more than 2 GB of memory, with a typical limit of 2^63 bytes. The actual value also depends on the overhead required for managing the data block. As a result, you can expect the maximum size of 2 GB minus overhead on 32-bit platforms, and 2^63 bytes minus overhead on 64-bit platforms. The number of elements that can be stored in a QByteArray is this maximum size.

When memory allocation fails, QByteArray throws a std::bad_alloc exception if the application is being compiled with exception support. Out of memory conditions in Qt containers are the only case where Qt will throw exceptions. If exceptions are disabled, then running out of memory is undefined behavior.

Note that the operating system may impose further limits on applications holding a lot of allocated memory, especially large, contiguous blocks. Such considerations, the configuration of such behavior or any mitigation are outside the scope of the QByteArray API.

C locale and ASCII functions#

QByteArray generally handles data as bytes, without presuming any semantics; where it does presume semantics, it uses the C locale and ASCII encoding. Standard Unicode encodings are supported by QString , other encodings may be supported using QStringEncoder and QStringDecoder to convert to Unicode. For locale-specific interpretation of text, use QLocale or QString .

C Strings#

Traditional C strings, also known as ‘\0’-terminated strings, are sequences of bytes, specified by a start-point and implicitly including each byte up to, but not including, the first ‘\0’ byte thereafter. Methods that accept such a pointer, without a length, will interpret it as this sequence of bytes. Such a sequence, by construction, cannot contain a ‘\0’ byte.

Other overloads accept a start-pointer and a byte-count; these use the given number of bytes, following the start address, regardless of whether any of them happen to be ‘\0’ bytes. In some cases, where there is no overload taking only a pointer, passing a length of -1 will cause the method to use the offset of the first ‘\0’ byte after the pointer as the length; a length of -1 should only be passed if the method explicitly says it does this (in which case it is typically a default argument).

Spacing Characters#

A frequent requirement is to remove spacing characters from a byte array ('\n', '\t', ' ', etc.). If you want to remove spacing from both ends of a QByteArray , use trimmed() . If you want to also replace each run of spacing characters with a single space character within the byte array, use simplified() . Only ASCII spacing characters are recognized for these purposes.

Number-String Conversions#

Functions that perform conversions between numeric data types and string representations are performed in the C locale, regardless of the user’s locale settings. Use QLocale to perform locale-aware conversions between numbers and strings.

Character Case#

In QByteArray , the notion of uppercase and lowercase and of case-independent comparison is limited to ASCII. Non-ASCII characters are treated as caseless, since their case depends on encoding. This affects functions that support a case insensitive option or that change the case of their arguments. Functions that this affects include compare() , isLower() , isUpper() , toLower() and toUpper() .

This issue does not apply to QString s since they represent characters using Unicode.

See also

QByteArrayView QString QBitArray

class Base64Option#

(inherits enum.Flag) This enum contains the options available for encoding and decoding Base64. Base64 is defined by RFC 4648, with the following options:

Constant

Description

QByteArray.Base64Encoding

(default) The regular Base64 alphabet, called simply “base64”

QByteArray.Base64UrlEncoding

An alternate alphabet, called “base64url”, which replaces two characters in the alphabet to be more friendly to URLs.

QByteArray.KeepTrailingEquals

(default) Keeps the trailing padding equal signs at the end of the encoded data, so the data is always a size multiple of four.

QByteArray.OmitTrailingEquals

Omits adding the padding equal signs at the end of the encoded data.

QByteArray.IgnoreBase64DecodingErrors

When decoding Base64-encoded data, ignores errors in the input; invalid characters are simply skipped. This enum value has been added in Qt 5.15.

QByteArray.AbortOnBase64DecodingErrors

When decoding Base64-encoded data, stops at the first decoding error. This enum value has been added in Qt 5.15.

Constant	Description
QByteArray.Base64Encoding	(default) The regular Base64 alphabet, called simply “base64”
QByteArray.Base64UrlEncoding	An alternate alphabet, called “base64url”, which replaces two characters in the alphabet to be more friendly to URLs.
QByteArray.KeepTrailingEquals	(default) Keeps the trailing padding equal signs at the end of the encoded data, so the data is always a size multiple of four.
QByteArray.OmitTrailingEquals	Omits adding the padding equal signs at the end of the encoded data.
QByteArray.IgnoreBase64DecodingErrors	When decoding Base64-encoded data, ignores errors in the input; invalid characters are simply skipped. This enum value has been added in Qt 5.15.
QByteArray.AbortOnBase64DecodingErrors	When decoding Base64-encoded data, stops at the first decoding error. This enum value has been added in Qt 5.15.

fromBase64Encoding() and fromBase64() ignore the KeepTrailingEquals and OmitTrailingEquals options. If the IgnoreBase64DecodingErrors option is specified, they will not flag errors in case trailing equal signs are missing or if there are too many of them. If instead the AbortOnBase64DecodingErrors is specified, then the input must either have no padding or have the correct amount of equal signs.

class Base64DecodingStatus#

__init__(arg__1)#

Parameters:: arg__1 – PyByteArray

__init__()

Constructs an empty byte array.

See also

isEmpty()

__init__(size, c)

Parameters:

size – int
c – int

Constructs a byte array of size size with every byte set to ch.

See also

fill()

__init__(arg__1[, size=-1])

Parameters:

arg__1 – str
size – int

Constructs a byte array containing the first size bytes of array data.

If data is 0, a null byte array is constructed.

If size is negative, data is assumed to point to a ‘\0’-terminated string and its length is determined dynamically.

QByteArray makes a deep copy of the string data.

See also

fromRawData()

__init__(arg__1)

Parameters:: arg__1 – PyBytes

__init__(arg__1)

Parameters:: arg__1 – QByteArray

Constructs a copy of other.

This operation takes constant time , because QByteArray is implicitly shared . This makes returning a QByteArray from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), taking linear time .

See also

operator=()

__getitem__()#

__len__()#

__mgetitem__()#

__msetitem__()#

__reduce__()#

Return type:: object

__repr__()#

Return type:: object

__setitem__()#

__str__()#

Return type:: object

append(s, len)#

Parameters:

s – str
len – int

Return type:

QByteArray

This is an overloaded function.

Appends the first len bytes starting at str to this byte array and returns a reference to this byte array. The bytes appended may include ‘\0’ bytes.

If len is negative, str will be assumed to be a ‘\0’-terminated string and the length to be copied will be determined automatically using qstrlen() .

If len is zero or str is null, nothing is appended to the byte array. Ensure that len is not longer than str.

append(count, c)

Parameters:

count – int
c – int

Return type:

QByteArray

This is an overloaded function.

Appends count copies of byte ch to this byte array and returns a reference to this byte array.

If count is negative or zero nothing is appended to the byte array.

append(a)

Parameters:: a – QByteArray
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Appends the byte array ba onto the end of this byte array.

Example:

x = QByteArray("free")
y = QByteArray("dom")
x.append(y)
# x == "freedom"

This is the same as insert( size() , ba).

Note: QByteArray is an implicitly shared class. Consequently, if you append to an empty byte array, then the byte array will just share the data held in ba. In this case, no copying of data is done, taking constant time . If a shared instance is modified, it will be copied (copy-on-write), taking linear time .

If the byte array being appended to is not empty, a deep copy of the data is performed, taking linear time .

The append() function is typically very fast ( constant time ), because QByteArray preallocates extra space at the end of the data, so it can grow without reallocating the entire array each time.

See also

operator+=() prepend() insert()

append(c)

Parameters:: c – int
Return type:: QByteArray

This is an overloaded function.

Appends the byte ch to this byte array.

append(a)

Parameters:: a – QByteArrayView
Return type:: QByteArray

This is an overloaded function.

Appends data to this byte array.

assign(v)#

Parameters:: v – QByteArrayView
Return type:: QByteArray

Replaces the contents of this byte array with a copy of v and returns a reference to this byte array.

The size of this byte array will be equal to the size of v.

This function only allocates memory if the size of v exceeds the capacity of this byte array or this byte array is shared.

assign(n, c)

Parameters:

n – int
c – int

Return type:

QByteArray

Replaces the contents of this byte array with n copies of c and returns a reference to this byte array.

The size of this byte array will be equal to n, which has to be non-negative.

This function will only allocate memory if n exceeds the capacity of this byte array or this byte array is shared.

See also

fill()

at(i)#

Parameters:: i – int
Return type:: int

Returns the byte at index position i in the byte array.

i must be a valid index position in the byte array (i.e., 0 <= i < size() ).

See also

operator[]()

back()#

Return type:: int

Returns the last byte in the byte array. Same as at(size() - 1).

This function is provided for STL compatibility.

Warning

Calling this function on an empty byte array constitutes undefined behavior.

See also

front() at() operator[]()

capacity()#

Return type:: int

Returns the maximum number of bytes that can be stored in the byte array without forcing a reallocation.

The sole purpose of this function is to provide a means of fine tuning QByteArray ‘s memory usage. In general, you will rarely ever need to call this function. If you want to know how many bytes are in the byte array, call size() .

Note

a statically allocated byte array will report a capacity of 0, even if it’s not empty.

Note

The free space position in the allocated memory block is undefined. In other words, one should not assume that the free memory is always located after the initialized elements.

See also

reserve() squeeze()

cbegin()#

Return type:: str

Returns a const STL-style iterator pointing to the first byte in the byte-array.

Warning

The returned iterator is invalidated on detachment or when the QByteArray is modified.

See also

begin() cend()

cend()#

Return type:: str

Returns a const STL-style iterator pointing just after the last byte in the byte-array.

Warning

The returned iterator is invalidated on detachment or when the QByteArray is modified.

See also

cbegin() end()

chop(n)#

Parameters:: n – int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Removes n bytes from the end of the byte array.

If n is greater than size() , the result is an empty byte array.

Example:

ba = QByteArray("STARTTLS\r\n")
ba.chop(2) # ba == "STARTTLS"
See also

truncate() resize() first()

chopped(len)#

Parameters:: len – int
Return type:: QByteArray

clear()#

Clears the contents of the byte array and makes it null.

See also

resize() isNull()

compare(a[, cs=Qt.CaseSensitive])#

Parameters:

a – QByteArrayView
cs – CaseSensitivity

Return type:

int

Returns an integer less than, equal to, or greater than zero depending on whether this QByteArray sorts before, at the same position as, or after the QByteArrayView bv. The comparison is performed according to case sensitivity cs.

See also

operator== Character Case

contains(bv)#

Parameters:: bv – QByteArrayView
Return type:: bool

Returns true if this byte array contains an occurrence of the sequence of bytes viewed by bv; otherwise returns false.

See also

indexOf() count()

contains(c)

Parameters:: c – int
Return type:: bool

This is an overloaded function.

Returns true if the byte array contains the byte ch; otherwise returns false.

count()#

Return type:: int

Note

This function is deprecated.

Use size() or length() instead.

This is an overloaded function.

Same as size() .

count(bv)

Parameters:: bv – QByteArrayView
Return type:: int

Returns the number of (potentially overlapping) occurrences of the sequence of bytes viewed by bv in this byte array.

See also

contains() indexOf()

count(c)

Parameters:: c – int
Return type:: int

This is an overloaded function.

Returns the number of occurrences of byte ch in the byte array.

See also

contains() indexOf()

data()#

Return type:: str

This is an overloaded function.

endsWith(bv)#

Parameters:: bv – QByteArrayView
Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns true if this byte array ends with the sequence of bytes viewed by bv; otherwise returns false.

Example:

url = QByteArray("http://qt-project.org/doc/qt-5.0/qtdoc/index.html")
if url.endsWith(".html"):
    ...

See also

startsWith() last()

endsWith(c)

Parameters:: c – int
Return type:: bool

This is an overloaded function.

Returns true if this byte array ends with byte ch; otherwise returns false.

erase(first, last)#

Parameters:

first – str
last – str

Return type:

char

erase(it)

Parameters:: it – str
Return type:: char

Removes the character denoted by it from the byte array. Returns an iterator to the character immediately after the erased character.

QByteArray ba = "abcdefg";
auto it = ba.erase(ba.cbegin()); // ba is now "bcdefg" and it points to "b"

fill(c[, size=-1])#

Parameters:

c – int
size – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Sets every byte in the byte array to ch. If size is different from -1 (the default), the byte array is resized to size size beforehand.

Example:

ba = QByteArray("Istambul")
ba.fill('o')
# ba == "oooooooo"
ba.fill('X', 2)
# ba == "XX"

See also

resize()

first(n)#

Parameters:: n – int
Return type:: QByteArray

static fromBase64(base64[, options=QByteArray.Base64Option.Base64Encoding])#

Parameters:

base64 – QByteArray
options – Combination of Base64Option

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a decoded copy of the Base64 array base64, using the options defined by options. If options contains IgnoreBase64DecodingErrors (the default), the input is not checked for validity; invalid characters in the input are skipped, enabling the decoding process to continue with subsequent characters. If options contains AbortOnBase64DecodingErrors, then decoding will stop at the first invalid character.

For example:

text = QByteArray.fromBase64("UXQgaXMgZ3JlYXQh")
text.data() # returns "Qt is great!"
QByteArray.fromBase64("PHA+SGVsbG8/PC9wPg==", QByteArray.Base64Encoding) # returns "<p>Hello?</p>"
QByteArray.fromBase64("PHA-SGVsbG8_PC9wPg==", QByteArray.Base64UrlEncoding) # returns "<p>Hello?</p>"

The algorithm used to decode Base64-encoded data is defined in RFC 4648.

Returns the decoded data, or, if the AbortOnBase64DecodingErrors option was passed and the input data was invalid, an empty byte array.

Note

The fromBase64Encoding() function is recommended in new code.

See also

toBase64() fromBase64Encoding()

static fromBase64Encoding(base64[, options=QByteArray.Base64Option.Base64Encoding])#

Parameters:

base64 – QByteArray
options – Combination of Base64Option

Return type:

FromBase64Result

static fromHex(hexEncoded)#

Parameters:: hexEncoded – QByteArray
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a decoded copy of the hex encoded array hexEncoded. Input is not checked for validity; invalid characters in the input are skipped, enabling the decoding process to continue with subsequent characters.

For example:

text = QByteArray.fromHex("517420697320677265617421")
text.data() # returns "Qt is great!"

See also

toHex()

static fromPercentEncoding(pctEncoded[, percent='%'])#

Parameters:

pctEncoded – QByteArray
percent – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Decodes input from URI/URL-style percent-encoding.

Returns a byte array containing the decoded text. The percent parameter allows use of a different character than ‘%’ (for instance, ‘_’ or ‘=’) as the escape character. Equivalent to input. percentDecoded (percent).

For example:

text = QByteArray.fromPercentEncoding("Qt%20is%20great%33")
qDebug("%s", text.data()) # reports "Qt is great!"

See also

percentDecoded()

static fromRawData(data, size)#

Parameters:

data – str
size – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Constructs a QByteArray that uses the first size bytes of the data array. The bytes are not copied. The QByteArray will contain the data pointer. The caller guarantees that data will not be deleted or modified as long as this QByteArray and any copies of it exist that have not been modified. In other words, because QByteArray is an implicitly shared class and the instance returned by this function contains the data pointer, the caller must not delete data or modify it directly as long as the returned QByteArray and any copies exist. However, QByteArray does not take ownership of data, so the QByteArray destructor will never delete the raw data, even when the last QByteArray referring to data is destroyed.

A subsequent attempt to modify the contents of the returned QByteArray or any copy made from it will cause it to create a deep copy of the data array before doing the modification. This ensures that the raw data array itself will never be modified by QByteArray .

Here is an example of how to read data using a QDataStream on raw data in memory without copying the raw data into a QByteArray :

 mydata = {
    '\x00', '\x00', '\x03', '\x84', '\x78', '\x9c', '\x3b', '\x76',
    '\xec', '\x18', '\xc3', '\x31', '\x0a', '\xf1', '\xcc', '\x99',
    ...
    '\x6d', '\x5b'

data = QByteArray.fromRawData(mydata, sizeof(mydata))
in = QDataStream(data, QIODevice.ReadOnly)
...

Warning

A byte array created with fromRawData() is not ‘\0’-terminated, unless the raw data contains a ‘\0’ byte at position size. While that does not matter for QDataStream or functions like indexOf() , passing the byte array to a function accepting a const char * expected to be ‘\0’-terminated will fail.

See also

setRawData() data() constData()

static fromStdString(s)#

Parameters:: s – str
Return type:: QByteArray

Returns a copy of the str string as a QByteArray .

See also

toStdString() fromStdString()

front()#

Return type:: int

Returns the first byte in the byte array. Same as at(0).

This function is provided for STL compatibility.

Warning

Calling this function on an empty byte array constitutes undefined behavior.

See also

back() at() operator[]()

indexOf(bv[, from=0])#

Parameters:

bv – QByteArrayView
from – int

Return type:

int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the index position of the start of the first occurrence of the sequence of bytes viewed by bv in this byte array, searching forward from index position from. Returns -1 if no match is found.

Example:

x = QByteArray("sticky question")
y = QByteArrayView("sti")
x.indexOf(y) # returns 0
x.indexOf(y, 1) # returns 10
x.indexOf(y, 10) # returns 10
x.indexOf(y, 11) # returns -1

See also

lastIndexOf() contains() count()

indexOf(c[, from=0])

Parameters:

c – int
from – int

Return type:

int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

This is an overloaded function.

Returns the index position of the start of the first occurrence of the byte ch in this byte array, searching forward from index position from. Returns -1 if no match is found.

Example:

ba = QByteArray("ABCBA")
ba.indexOf("B") # returns 1
ba.indexOf("B", 1) # returns 1
ba.indexOf("B", 2) # returns 3
ba.indexOf("X") # returns -1

See also

lastIndexOf() contains()

insert(i, s, len)#

Parameters:

i – int
s – str
len – int

Return type:

QByteArray

This is an overloaded function.

Inserts len bytes, starting at data, at position i in the byte array.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

insert(i, count, c)

Parameters:

i – int
count – int
c – int

Return type:

QByteArray

This is an overloaded function.

Inserts count copies of byte ch at index position i in the byte array.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

insert(i, s)

Parameters:

i – int
s – str

Return type:

QByteArray

Inserts s at index position i and returns a reference to this byte array.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

The function is equivalent to insert(i, QByteArrayView(s))

See also

append() prepend() replace() remove()

insert(i, data)

Parameters:

i – int
data – QByteArray

Return type:

QByteArray

Inserts data at index position i and returns a reference to this byte array.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

See also

append() prepend() replace() remove()

insert(i, c)

Parameters:

i – int
c – int

Return type:

QByteArray

This is an overloaded function.

Inserts byte ch at index position i in the byte array.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

insert(i, data)

Parameters:

i – int
data – QByteArrayView

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Inserts data at index position i and returns a reference to this byte array.

Example:

ba = QByteArray("Meal")
ba.insert(1, QByteArrayView("ontr"))
# ba == "Montreal"

For large byte arrays, this operation can be slow ( linear time ), because it requires moving all the bytes at indexes i and above by at least one position further in memory.

This array grows to accommodate the insertion. If i is beyond the end of the array, the array is first extended with space characters to reach this i.

See also

append() prepend() replace() remove()

isEmpty()#

Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns true if the byte array has size 0; otherwise returns false.

Example:

QByteArray().isEmpty() # returns true
QByteArray("").isEmpty() # returns true
QByteArray("abc").isEmpty() # returns false

See also

size()

isLower()#

Return type:: bool

Returns true if this byte array is lowercase, that is, if it’s identical to its toLower() folding.

Note that this does not mean that the byte array only contains lowercase letters; only that it contains no ASCII uppercase letters.

See also

isUpper() toLower()

isNull()#

Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns true if this byte array is null; otherwise returns false.

Example:

QByteArray().isNull() # returns true
QByteArray("").isNull() # returns false
QByteArray("abc").isNull() # returns false

Qt makes a distinction between null byte arrays and empty byte arrays for historical reasons. For most applications, what matters is whether or not a byte array contains any data, and this can be determined using isEmpty() .

See also

isEmpty()

isSharedWith(other)#

Parameters:: other – QByteArray
Return type:: bool

isUpper()#

Return type:: bool

Returns true if this byte array is uppercase, that is, if it’s identical to its toUpper() folding.

Note that this does not mean that the byte array only contains uppercase letters; only that it contains no ASCII lowercase letters.

See also

isLower() toUpper()

isValidUtf8()#

Return type:: bool

Returns true if this byte array contains valid UTF-8 encoded data, or false otherwise.

last(n)#

Parameters:: n – int
Return type:: QByteArray

lastIndexOf(bv, from)#

Parameters:

bv – QByteArrayView
from – int

Return type:

int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the index position of the start of the last occurrence of the sequence of bytes viewed by bv in this byte array, searching backward from index position from.

If from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.

Returns -1 if no match is found.

Example:

x = QByteArray("crazy azimuths")
y = QByteArrayView("az")
x.lastIndexOf(y) # returns 6
x.lastIndexOf(y, 6) # returns 6
x.lastIndexOf(y, 5) # returns 2
x.lastIndexOf(y, 1) # returns -1

Note

When searching for a 0-length bv, the match at the end of the data is excluded from the search by a negative from, even though -1 is normally thought of as searching from the end of the byte array: the match at the end is after the last character, so it is excluded. To include such a final empty match, either give a positive value for from or omit the from parameter entirely.

See also

indexOf() contains() count()

lastIndexOf(c[, from=-1])

Parameters:

c – int
from – int

Return type:

int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

This is an overloaded function.

Returns the index position of the start of the last occurrence of byte ch in this byte array, searching backward from index position from. If from is -1 (the default), the search starts at the last byte (at index size() - 1). Returns -1 if no match is found.

Example:

ba = QByteArray("ABCBA")
ba.lastIndexOf("B") # returns 3
ba.lastIndexOf("B", 3) # returns 3
ba.lastIndexOf("B", 2) # returns 1
ba.lastIndexOf("X") # returns -1

See also

indexOf() contains()

lastIndexOf(bv)

Parameters:: bv – QByteArrayView
Return type:: int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

This is an overloaded function.

Returns the index position of the start of the last occurrence of the sequence of bytes viewed by bv in this byte array, searching backward from the end of the byte array. Returns -1 if no match is found.

Example:

x = QByteArray("crazy azimuths")
y = QByteArrayView("az")
x.lastIndexOf(y) # returns 6
x.lastIndexOf(y, 6) # returns 6
x.lastIndexOf(y, 5) # returns 2
x.lastIndexOf(y, 1) # returns -1

See also

indexOf() contains() count()

left(n)#

Parameters:: n – int
Return type:: QByteArray

leftJustified(width[, fill=' '[, truncate=false]])#

Parameters:

width – int
fill – int
truncate – bool

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a byte array of size width that contains this byte array padded with the fill byte.

If truncate is false and the size() of the byte array is more than width, then the returned byte array is a copy of this byte array.

If truncate is true and the size() of the byte array is more than width, then any bytes in a copy of the byte array after position width are removed, and the copy is returned.

Example:

x = QByteArray("apple")
y = x.leftJustified(8, '.') # y == "apple..."

See also

rightJustified()

length()#

Return type:: int

Same as size() .

mid(index[, len=-1])#

Parameters:

index – int
len – int

Return type:

QByteArray

static number(arg__1[, base=10])#

Parameters:

arg__1 – int
base – int

Return type:

QByteArray

This is an overloaded function.

See also

toLongLong()

static number(arg__1[, base=10])

Parameters:

arg__1 – int
base – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a byte-array representing the whole number n as text.

Returns a byte array containing a string representing n, using the specified base (ten by default). Bases 2 through 36 are supported, using letters for digits beyond 9: A is ten, B is eleven and so on.

Example:

n = 63
QByteArray.number(n) # returns "63"
QByteArray.number(n, 16) # returns "3f"
QByteArray.number(n, 16).toUpper() # returns "3F"

Note

The format of the number is not localized; the default C locale is used regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

See also

setNum() toInt()

static number(arg__1[, format='g'[, precision=6]])

Parameters:

arg__1 – float
format – int
precision – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

This is an overloaded function.

Returns a byte-array representing the floating-point number n as text.

Returns a byte array containing a string representing n, with a given format and precision, with the same meanings as for number(double, char, int) . For example:

ba = QByteArray.number(12.3456, 'E', 3)
# ba == 1.235E+01
See also

toDouble() FloatingPointPrecisionOption

__ne__(arg__1)#

Parameters:: arg__1 – PyUnicode

__ne__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is not equal to byte array a2; otherwise returns false.

See also

compare()

__ne__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is not equal to the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

You can disable this operator by defining QT_NO_CAST_FROM_ASCII when you compile your applications. You then need to call fromUtf8() , fromLatin1() , or fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.

__add__(rhs)#

Parameters:: rhs – str
Return type:: QByteArray

This is an overloaded function.

Returns a byte array that is the result of concatenating byte array a1 and ‘\0’-terminated string a2.

__add__(s)

Parameters:: s – str
Return type:: str

__add__(s)

Parameters:: s – str
Return type:: str

__add__(rhs)

Parameters:: rhs – QByteArray
Return type:: QByteArray

Returns a byte array that is the result of concatenating byte array a1 and byte array a2.

See also

operator+=()

__add__(a2)

Parameters:: a2 – QByteArray
Return type:: QByteArray

Returns a byte array that is the result of concatenating byte array a1 and byte array a2.

See also

operator+=()

__add__(a2)

Parameters:: a2 – int
Return type:: QByteArray

This is an overloaded function.

Returns a byte array that is the result of concatenating byte array a1 and byte a2.

__add__(rhs)

Parameters:: rhs – int
Return type:: QByteArray

This is an overloaded function.

Returns a byte array that is the result of concatenating byte array a1 and byte a2.

__add__(arg__1)

Parameters:: arg__1 – PyByteArray
Return type:: QByteArray

__add__(arg__1)

Parameters:: arg__1 – PyBytes

__add__(arg__1)

Parameters:: arg__1 – PyByteArray
Return type:: QByteArray

__iadd__(arg__1)#

Parameters:: arg__1 – PyByteArray
Return type:: QByteArray

__iadd__(a)

Parameters:: a – QByteArrayView
Return type:: QByteArray

__iadd__(c)

Parameters:: c – int
Return type:: QByteArray

This is an overloaded function.

Appends the byte ch onto the end of this byte array and returns a reference to this byte array.

__iadd__(a)

Parameters:: a – QByteArray
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Appends the byte array ba onto the end of this byte array and returns a reference to this byte array.

Example:

x = QByteArray("free")
y = QByteArray("dom")
x += y
# x == "freedom"

If the byte array being appended to is not empty, a deep copy of the data is performed, taking linear time .

This operation typically does not suffer from allocation overhead, because QByteArray preallocates extra space at the end of the data so that it may grow without reallocating for each append operation.

See also

append() prepend()

__lt__(arg__1)#

Parameters:: arg__1 – PyUnicode

__lt__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is lexically less than byte array a2; otherwise returns false.

See also

compare()

__lt__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is lexically less than the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

__lt__(a2)

Parameters:: a2 – str
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is lexically less than the ‘\0’-terminated string a2; otherwise returns false.

See also

compare()

__le__(arg__1)#

Parameters:: arg__1 – PyUnicode

__le__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is lexically less than or equal to the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

__le__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is lexically less than or equal to byte array a2; otherwise returns false.

See also

compare()

__eq__(arg__1)#

Parameters:: arg__1 – PyUnicode

__eq__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is equal to byte array a2; otherwise returns false.

See also

compare()

__eq__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is equal to the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

__gt__(arg__1)#

Parameters:: arg__1 – PyUnicode

__gt__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is lexically greater than byte array a2; otherwise returns false.

See also

compare()

__gt__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is lexically greater than the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

__ge__(arg__1)#

Parameters:: arg__1 – PyUnicode

__ge__(s2)

Parameters:: s2 – str
Return type:: bool

Returns true if this byte array is greater than or equal to the UTF-8 encoding of str; otherwise returns false.

The comparison is case sensitive.

__ge__(a2)

Parameters:: a2 – QByteArray
Return type:: bool

This is an overloaded function.

Returns true if byte array a1 is lexically greater than or equal to byte array a2; otherwise returns false.

See also

compare()

operator(i)#

Parameters:: i – int
Return type:: int

This is an overloaded function.

Same as at(i).

percentDecoded([percent='%'])#

Parameters:: percent – int
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Decodes URI/URL-style percent-encoding.

Returns a byte array containing the decoded text. The percent parameter allows use of a different character than ‘%’ (for instance, ‘_’ or ‘=’) as the escape character.

For example:

encoded = QByteArray("Qt%20is%20great%33")
decoded = encoded.percentDecoded() # Set to "Qt is great!"

Note

Given invalid input (such as a string containing the sequence “%G5”, which is not a valid hexadecimal number) the output will be invalid as well. As an example: the sequence “%G5” could be decoded to ‘W’.

prepend(a)#

Parameters:: a – QByteArrayView
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Prepends the byte array view ba to this byte array and returns a reference to this byte array.

This operation is typically very fast ( constant time ), because QByteArray preallocates extra space at the beginning of the data, so it can grow without reallocating the entire array each time.

Example:

x = QByteArray("ship")
y = QByteArray("air")
x.prepend(y)
# x == "airship"

This is the same as insert(0, ba).

See also

append() insert()

prepend(c)

Parameters:: c – int
Return type:: QByteArray

This is an overloaded function.

Prepends the byte ch to this byte array.

prepend(a)

Parameters:: a – QByteArray
Return type:: QByteArray

This is an overloaded function.

Prepends ba to this byte array.

prepend(s, len)

Parameters:

s – str
len – int

Return type:

QByteArray

This is an overloaded function.

Prepends len bytes starting at str to this byte array. The bytes prepended may include ‘\0’ bytes.

prepend(count, c)

Parameters:

count – int
c – int

Return type:

QByteArray

This is an overloaded function.

Prepends count copies of byte ch to this byte array.

push_back(a)#

Parameters:: a – QByteArrayView

This is an overloaded function.

Same as append(str).

push_front(a)#

Parameters:: a – QByteArrayView

This is an overloaded function.

Same as prepend(str).

remove(index, len)#

Parameters:

index – int
len – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Removes len bytes from the array, starting at index position pos, and returns a reference to the array.

If pos is out of range, nothing happens. If pos is valid, but pos + len is larger than the size of the array, the array is truncated at position pos.

Example:

ba = QByteArray("Montreal")
ba.remove(1, 4)
# ba == "Meal"

Element removal will preserve the array’s capacity and not reduce the amount of allocated memory. To shed extra capacity and free as much memory as possible, call squeeze() after the last change to the array’s size.

See also

insert() replace() squeeze()

removeAt(pos)#

Parameters:: pos – int
Return type:: QByteArray

Removes the character at index pos. If pos is out of bounds (i.e. pos >= size() ) this function does nothing.

See also

remove()

removeFirst()#

Return type:: QByteArray

Removes the first character in this byte array. If the byte array is empty, this function does nothing.

See also

remove()

removeLast()#

Return type:: QByteArray

Removes the last character in this byte array. If the byte array is empty, this function does nothing.

See also

remove()

repeated(times)#

Parameters:: times – int
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of this byte array repeated the specified number of times.

If times is less than 1, an empty byte array is returned.

Example:

ba = QByteArray("ab")
ba.repeated(4) # returns "abababab"

replace(index, len, s, alen)#

Parameters:

index – int
len – int
s – str
alen – int

Return type:

QByteArray

This is an overloaded function.

Replaces len bytes from index position pos with alen bytes starting at position after. The bytes inserted may include ‘\0’ bytes.

replace(index, len, s)

Parameters:

index – int
len – int
s – QByteArrayView

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Replaces len bytes from index position pos with the byte array after, and returns a reference to this byte array.

Example:

x = QByteArray("Say yes!")
y = QByteArray("no")
x.replace(4, 3, y)
# x == "Say no!"

See also

insert() remove()

replace(before, after)

Parameters:

before – int
after – int

Return type:

QByteArray

This is an overloaded function.

Replaces every occurrence of the byte before with the byte after.

replace(before, after)

Parameters:

before – int
after – QByteArrayView

Return type:

QByteArray

This is an overloaded function.

Replaces every occurrence of the byte before with the byte array after.

replace(before, bsize, after, asize)

Parameters:

before – str
bsize – int
after – str
asize – int

Return type:

QByteArray

This is an overloaded function.

Replaces every occurrence of the bsize bytes starting at before with the asize bytes starting at after. Since the sizes of the strings are given by bsize and asize, they may contain ‘\0’ bytes and do not need to be ‘\0’-terminated.

replace(before, after)

Parameters:

before – QByteArrayView
after – QByteArrayView

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

This is an overloaded function.

Replaces every occurrence of the byte array before with the byte array after.

Example:

ba = QByteArray("colour behaviour flavour neighbour")
ba.replace(QByteArray("ou"), QByteArray("o"))
# ba == "color behavior flavor neighbor"

reserve(size)#

Parameters:: size – int

Attempts to allocate memory for at least size bytes.

If you know in advance how large the byte array will be, you can call this function, and if you call resize() often you are likely to get better performance.

If in doubt about how much space shall be needed, it is usually better to use an upper bound as size, or a high estimate of the most likely size, if a strict upper bound would be much bigger than this. If size is an underestimate, the array will grow as needed once the reserved size is exceeded, which may lead to a larger allocation than your best overestimate would have and will slow the operation that triggers it.

Warning

reserve() reserves memory but does not change the size of the byte array. Accessing data beyond the end of the byte array is undefined behavior. If you need to access memory beyond the current end of the array, use resize() .

The sole purpose of this function is to provide a means of fine tuning QByteArray ‘s memory usage. In general, you will rarely ever need to call this function.

See also

squeeze() capacity()

resize(size)#

Parameters:: size – int

Sets the size of the byte array to size bytes.

If size is greater than the current size, the byte array is extended to make it size bytes with the extra bytes added to the end. The new bytes are uninitialized.

If size is less than the current size, bytes beyond position size are excluded from the byte array.

Note

While resize() will grow the capacity if needed, it never shrinks capacity. To shed excess capacity, use squeeze() .

See also

size() truncate() squeeze()

resize(size, c)

Parameters:

size – int
c – int

Sets the size of the byte array to newSize bytes.

If newSize is greater than the current size, the byte array is extended to make it newSize bytes with the extra bytes added to the end. The new bytes are initialized to c.

If newSize is less than the current size, bytes beyond position newSize are excluded from the byte array.

Note

While resize() will grow the capacity if needed, it never shrinks capacity. To shed excess capacity, use squeeze() .

See also

size() truncate() squeeze()

right(n)#

Parameters:: n – int
Return type:: QByteArray

rightJustified(width[, fill=' '[, truncate=false]])#

Parameters:

width – int
fill – int
truncate – bool

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a byte array of size width that contains the fill byte followed by this byte array.

If truncate is false and the size of the byte array is more than width, then the returned byte array is a copy of this byte array.

If truncate is true and the size of the byte array is more than width, then the resulting byte array is truncated at position width.

Example:

x = QByteArray("apple")
y = x.rightJustified(8, '.') # y == "...apple"

See also

leftJustified()

setNum(arg__1[, format='g'[, precision=6]])#

Parameters:

arg__1 – float
format – int
precision – int

Return type:

QByteArray

This is an overloaded function.

Represent the floating-point number n as text.

Sets this byte array to a string representing n, with a given format and precision (with the same meanings as for number(double, char, int) ), and returns a reference to this byte array.

See also

toDouble() FloatingPointPrecisionOption

setNum(arg__1[, base=10])

Parameters:

arg__1 – int
base – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Represent the whole number n as text.

Sets this byte array to a string representing n in base base (ten by default) and returns a reference to this byte array. Bases 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Example:

ba = QByteArray()
n = 63
ba.setNum(n) # ba == "63"
ba.setNum(n, 16) # ba == "3f"

Note

The format of the number is not localized; the default C locale is used regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

See also

number() toInt()

setNum(arg__1[, base=10])

Parameters:

arg__1 – int
base – int

Return type:

QByteArray

This is an overloaded function.

See also

toLongLong()

setRawData(a, n)#

Parameters:

a – str
n – int

Return type:

QByteArray

Resets the QByteArray to use the first size bytes of the data array. The bytes are not copied. The QByteArray will contain the data pointer. The caller guarantees that data will not be deleted or modified as long as this QByteArray and any copies of it exist that have not been modified.

This function can be used instead of fromRawData() to re-use existing QByteArray objects to save memory re-allocations.

See also

fromRawData() data() constData()

shrink_to_fit()#

This function is provided for STL compatibility. It is equivalent to squeeze() .

simplified()#

Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of this byte array that has spacing characters removed from the start and end, and in which each sequence of internal spacing characters is replaced with a single space.

The spacing characters are those for which the standard C++ isspace() function returns true in the C locale; these are the ASCII characters tabulation ‘\t’, line feed ‘\n’, carriage return ‘\r’, vertical tabulation ‘\v’, form feed ‘\f’, and space ‘ ‘.

Example:

ba = QByteArray(" lots\t of\nwhitespace\r\n ")
ba = ba.simplified()
# ba == "lots of whitespace"

See also

trimmed() SpecialCharacter Spacing Characters

size()#

Return type:: int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the number of bytes in this byte array.

The last byte in the byte array is at position size() - 1. In addition, QByteArray ensures that the byte at position size() is always ‘\0’, so that you can use the return value of data() and constData() as arguments to functions that expect ‘\0’-terminated strings. If the QByteArray object was created from a raw data that didn’t include the trailing ‘\0’-termination byte, then QByteArray doesn’t add it automatically unless a deep copy is created.

Example:

ba = QByteArray("Hello")
n = ba.size() # n == 5
ba.data()[0] # returns 'H'
ba.data()[4] # returns 'o'
ba.data()[5] # returns '\0'

See also

isEmpty() resize()

sliced(pos)#

Parameters:: pos – int
Return type:: QByteArray

sliced(pos, n)

Parameters:

pos – int
n – int

Return type:

QByteArray

split(sep)#

Parameters:: sep – int
Return type:: .list of QByteArray

Splits the byte array into subarrays wherever sep occurs, and returns the list of those arrays. If sep does not match anywhere in the byte array, split() returns a single-element list containing this byte array.

squeeze()#

Releases any memory not required to store the array’s data.

The sole purpose of this function is to provide a means of fine tuning QByteArray ‘s memory usage. In general, you will rarely ever need to call this function.

See also

reserve() capacity()

startsWith(c)#

Parameters:: c – int
Return type:: bool

This is an overloaded function.

Returns true if this byte array starts with byte ch; otherwise returns false.

startsWith(bv)

Parameters:: bv – QByteArrayView
Return type:: bool

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns true if this byte array starts with the sequence of bytes viewed by bv; otherwise returns false.

Example:

url = QByteArray("ftp://ftp.qt-project.org/")
if url.startsWith("ftp:"):
    ...

See also

endsWith() first()

swap(other)#

Parameters:: other – QByteArray

Swaps byte array other with this byte array. This operation is very fast and never fails.

toBase64([options=QByteArray.Base64Option.Base64Encoding])#

Parameters:: options – Combination of Base64Option
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of the byte array, encoded using the options options.

text = QByteArray("Qt is great!")
text.toBase64() # returns "UXQgaXMgZ3JlYXQh"
text = QByteArray("")
text.toBase64(QByteArray.Base64Encoding | QByteArray.OmitTrailingEquals) # returns "PHA+SGVsbG8/PC9wPg"
text.toBase64(QByteArray.Base64Encoding) # returns "PHA+SGVsbG8/PC9wPg=="
text.toBase64(QByteArray.Base64UrlEncoding) # returns "PHA-SGVsbG8_PC9wPg=="
text.toBase64(QByteArray.Base64UrlEncoding | QByteArray.OmitTrailingEquals) # returns "PHA-SGVsbG8_PC9wPg"

The algorithm used to encode Base64-encoded data is defined in RFC 4648.

See also

fromBase64()

toDouble()#

Return type:: float

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the byte array converted to a double value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

string = QByteArray("1234.56")
ok = bool()
a = string.toDouble(ok) # a == 1234.56, ok == true
string = "1234.56 Volt"
a = str.toDouble(ok) # a == 0, ok == false

Warning

The QByteArray content may only contain valid numerical characters which includes the plus/minus sign, the character e used in scientific notation, and the decimal point. Including the unit or additional characters leads to a conversion error.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

This function ignores leading and trailing whitespace.

See also

number()

toFloat()#

Return type:: float

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the byte array converted to a float value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

string = QByteArray("1234.56")
ok = bool()
a = string.toFloat(ok) # a == 1234.56, ok == true
string = "1234.56 Volt"
a = str.toFloat(ok) # a == 0, ok == false

Warning

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

This function ignores leading and trailing whitespace.

See also

number()

toHex([separator='\0'])#

Parameters:: separator – int
Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a hex encoded copy of the byte array.

The hex encoding uses the numbers 0-9 and the letters a-f.

If separator is not ‘\0’, the separator character is inserted between the hex bytes.

Example:

macAddress = QByteArray.fromHex("123456abcdef")
macAddress.toHex(':') # returns "12:34:56:ab:cd:ef"
macAddress.toHex(0) # returns "123456abcdef"

See also

fromHex()

toInt([base=10])#

Parameters:: base – int
Return type:: int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the byte array converted to an int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

If base is 0, the base is determined automatically using the following rules: If the byte array begins with “0x”, it is assumed to be hexadecimal (base 16); otherwise, if it begins with “0b”, it is assumed to be binary (base 2); otherwise, if it begins with “0”, it is assumed to be octal (base 8); otherwise it is assumed to be decimal.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

str = QByteArray("FF")
ok = bool()
hex = str.toInt(ok, 16) # hex == 255, ok == true
dec = str.toInt(ok, 10) # dec == 0, ok == false

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toLong([base=10])#

Parameters:: base – int
Return type:: int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns the byte array converted to a long int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

str = QByteArray("FF")
ok = bool()
hex = str.toLong(ok, 16) # hex == 255, ok == true
dec = str.toLong(ok, 10) # dec == 0, ok == false

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toLongLong([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to a long long using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toLower()#

Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of the byte array in which each ASCII uppercase letter converted to lowercase.

Example:

x = QByteArray("Qt by THE QT COMPANY")
y = x.toLower()
# y == "qt by the qt company"

See also

isLower() toUpper() Character Case

toPercentEncoding([exclude=QByteArray()[, include=QByteArray()[, percent='%']]])#

Parameters:

exclude – QByteArray
include – QByteArray
percent – int

Return type:

QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a URI/URL-style percent-encoded copy of this byte array. The percent parameter allows you to override the default ‘%’ character for another.

By default, this function will encode all bytes that are not one of the following:

ALPHA (“a” to “z” and “A” to “Z”) / DIGIT (0 to 9) / “-” / “.” / “_” / “~”

To prevent bytes from being encoded pass them to exclude. To force bytes to be encoded pass them to include. The percent character is always encoded.

Example:

QByteArray text = "{a fishy string?}"
QByteArray ba = text.toPercentEncoding("{}", "s")
qDebug("%s", ba.constData())
# prints "{a fi%73hy %73tring%3F}"

The hex encoding uses the numbers 0-9 and the uppercase letters A-F.

See also

fromPercentEncoding() toPercentEncoding()

toShort([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to a short using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toStdString()#

Return type:: str

Returns a std::string object with the data contained in this QByteArray .

This operator is mostly useful to pass a QByteArray to a function that accepts a std::string object.

See also

fromStdString() toStdString()

toUInt([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to an unsigned int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toULong([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to an unsigned long int using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toULongLong([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to an unsigned long long using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toUShort([base=10])#

Parameters:: base – int
Return type:: int

Returns the byte array converted to an unsigned short using base base, which is ten by default. Bases 0 and 2 through 36 are supported, using letters for digits beyond 9; A is ten, B is eleven and so on.

Returns 0 if the conversion fails.

If ok is not None, failure is reported by setting *``ok`` to false, and success by setting *``ok`` to true.

Note

The conversion of the number is performed in the default C locale, regardless of the user’s locale. Use QLocale to perform locale-aware conversions between numbers and strings.

Note

Support for the “0b” prefix was added in Qt 6.4.

See also

number()

toUpper()#

Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of the byte array in which each ASCII lowercase letter converted to uppercase.

Example:

x = QByteArray("Qt by THE QT COMPANY")
y = x.toUpper()
# y == "QT BY THE QT COMPANY"

See also

isUpper() toLower() Character Case

trimmed()#

Return type:: QByteArray

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Returns a copy of this byte array with spacing characters removed from the start and end.

Example:

ba = QByteArray(" lots\t of\nwhitespace\r\n ")
ba = ba.trimmed()
# ba == "lots\t of\nwhitespace"

Unlike simplified() , trimmed() leaves internal spacing unchanged.

See also

simplified() SpecialCharacter Spacing Characters

truncate(pos)#

Parameters:: pos – int

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Truncates the byte array at index position pos.

If pos is beyond the end of the array, nothing happens.

Example:

ba = QByteArray("Stockholm")
ba.truncate(5) # ba == "Stock"

See also

chop() resize() first()