QByteArray Class

Member Function Documentation

It returns the maximum number of elements that the byte array can theoretically hold. In practice, the number can be much smaller, limited by the amount of memory available to the system.

This function was introduced in Qt 6.8.

Returns a pointer to the data stored in the byte array. The pointer can be used to access the bytes that compose the array. The data is '\0'-terminated.

The pointer remains valid as long as no detach happens and the QByteArray is not modified.

This operator is mostly useful to pass a byte array to a function that accepts a const char *.

You can disable this operator by defining QT_NO_CAST_FROM_BYTEARRAY when you compile your applications.

Note: A QByteArray can store any byte values including '\0's, but most functions that take char * arguments assume that the data ends at the first '\0' they encounter.

See also constData().

Returns a byte array that contains the first len bytes of this byte array.

If you know that len cannot be out of bounds, use first() instead in new code, because it is faster.

The entire byte array is returned if len is greater than size().

Returns an empty QByteArray if len is smaller than 0.

See also first(), last(), startsWith(), chopped(), chop(), and truncate().

Returns a byte array that contains the last len bytes of this byte array.

If you know that len cannot be out of bounds, use last() instead in new code, because it is faster.

The entire byte array is returned if len is greater than size().

Returns an empty QByteArray if len is smaller than 0.

See also endsWith(), last(), first(), sliced(), chopped(), chop(), truncate(), and slice().

Returns a byte array containing len bytes from this byte array, starting at position pos.

If you know that pos and len cannot be out of bounds, use sliced() instead in new code, because it is faster.

If len is -1 (the default), or pos + len >= size(), returns a byte array containing all bytes starting at position pos until the end of the byte array.

See also first(), last(), sliced(), chopped(), chop(), truncate(), and slice().

Returns the first n bytes of the byte array.

Example:

QByteArray x("Pineapple");
QByteArray y = x.first(4);
// y == "Pine"

This function was introduced in Qt 6.0.

See also last(), sliced(), startsWith(), chopped(), chop(), truncate(), and slice().

Returns the last n bytes of the byte array.

Example:

QByteArray x("Pineapple");
QByteArray y = x.last(5);
// y == "apple"

This function was introduced in Qt 6.0.

See also first(), sliced(), endsWith(), chopped(), chop(), truncate(), and slice().

Returns a byte array containing the n bytes of this object starting at position pos.

Example:

QByteArray x("Five pineapples");
QByteArray y = x.sliced(5, 4);     // y == "pine"
QByteArray z = x.sliced(5);        // z == "pineapples"

This function was introduced in Qt 6.0.

See also first(), last(), chopped(), chop(), truncate(), and slice().

This is an overloaded function.

Returns a byte array containing the bytes starting at position pos in this object, and extending to the end of this object.

This function was introduced in Qt 6.0.

See also first(), last(), chopped(), chop(), truncate(), and slice().

Returns a byte array that contains the leftmost size() - len bytes of this byte array.

See also endsWith(), first(), last(), sliced(), chop(), truncate(), and slice().

This is an overloaded function.

Decodes 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:

void process(const QByteArray &);

if (auto result = QByteArray::fromBase64Encoding(encodedData))
    process(*result);

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

Returns a QByteArrayFromBase64Result object, containing the decoded data and a flag telling whether decoding was successful. If the AbortOnBase64DecodingErrors option was passed and the input data was invalid, it is unspecified what the decoded data contains.

See also toBase64().

[constexpr noexcept] QByteArray::QByteArray()

Constructs an empty byte array.

See also isEmpty().

QByteArray::QByteArray(const char *data, qsizetype size = -1)

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().

QByteArray::QByteArray(qsizetype size, Qt::Initialization)

Constructs a byte array of size size with uninitialized contents.

QByteArray::QByteArray(qsizetype size, char ch)

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

See also fill().

[noexcept] QByteArray::QByteArray(const QByteArray &other)

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=().

[noexcept] QByteArray::QByteArray(QByteArray &&other)

Move-constructs a QByteArray instance, making it point at the same object that other was pointing to.

[noexcept] QByteArray::~QByteArray()

Destroys the byte array.

QByteArray &QByteArray::append(const QByteArray &ba)

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

Example:

QByteArray x("free");
QByteArray y("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(), and insert().

QByteArray &QByteArray::append(QByteArrayView data)

This is an overloaded function.

Appends data to this byte array.

QByteArray &QByteArray::append(char ch)

This is an overloaded function.

Appends the byte ch to this byte array.

QByteArray &QByteArray::append(const char *str)

This is an overloaded function.

Appends the '\0'-terminated string str to this byte array.

QByteArray &QByteArray::append(const char *str, qsizetype len)

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.

QByteArray &QByteArray::append(qsizetype count, char ch)

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.

[since 6.6] QByteArray &QByteArray::assign(QByteArrayView v)

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.

This function was introduced in Qt 6.6.

[since 6.6] template <typename InputIterator, QByteArray::if_input_iterator<InputIterator> = true> QByteArray &QByteArray::assign(InputIterator first, InputIterator last)

Replaces the contents of this byte array with a copy of the elements in the iterator range [first, last) and returns a reference to this byte array.

The size of this byte array will be equal to the number of elements in the range [first, last).

This function will only allocate memory if the number of elements in the range exceeds the capacity of this byte array or this byte array is shared.

This function was introduced in Qt 6.6.

[since 6.6] QByteArray &QByteArray::assign(qsizetype n, char c)

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.

This function was introduced in Qt 6.6.

See also fill().

char QByteArray::at(qsizetype i) const

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[]().

char &QByteArray::back()

Returns a reference to the last byte in the byte array. Same as operator[](size() - 1).

This function is provided for STL compatibility.

See also front(), at(), and operator[]().

char QByteArray::back() const

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

This function is provided for STL compatibility.

See also front(), at(), and operator[]().

QByteArray::iterator QByteArray::begin()

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

See also constBegin() and end().

[noexcept] QByteArray::const_iterator QByteArray::begin() const

This function overloads begin().

qsizetype QByteArray::capacity() const

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().

See also reserve() and squeeze().

[noexcept] QByteArray::const_iterator QByteArray::cbegin() const

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

See also begin() and cend().

[noexcept] QByteArray::const_iterator QByteArray::cend() const

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

See also cbegin() and end().

void QByteArray::chop(qsizetype n)

Removes n bytes from the end of the byte array.

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

Example:

QByteArray ba("STARTTLS\r\n");
ba.chop(2);                 // ba == "STARTTLS"

See also truncate(), resize(), and first().

void QByteArray::clear()

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

See also resize() and isNull().

[noexcept, since 6.0] int QByteArray::compare(QByteArrayView bv, Qt::CaseSensitivity cs = Qt::CaseSensitive) const

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.

This function was introduced in Qt 6.0.

See also operator== and Character Case.

[noexcept] QByteArray::const_iterator QByteArray::constBegin() const

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

See also begin() and constEnd().

[noexcept] const char *QByteArray::constData() const

Returns a pointer to the const data stored in the byte array. The pointer can be used to access the bytes that compose the array. The data is '\0'-terminated unless the QByteArray object was created from raw data.

The pointer remains valid as long as no detach happens and the QByteArray is not modified.

This function is mostly useful to pass a byte array to a function that accepts a const char *.

Note: A QByteArray can store any byte values including '\0's, but most functions that take char * arguments assume that the data ends at the first '\0' they encounter.

See also data(), operator[](), and fromRawData().

[noexcept] QByteArray::const_iterator QByteArray::constEnd() const

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

See also constBegin() and end().

[since 6.0] bool QByteArray::contains(QByteArrayView bv) const

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

This function was introduced in Qt 6.0.

See also indexOf() and count().

bool QByteArray::contains(char ch) const

This is an overloaded function.

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

[since 6.0] qsizetype QByteArray::count(QByteArrayView bv) const

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

This function was introduced in Qt 6.0.

See also contains() and indexOf().

qsizetype QByteArray::count(char ch) const

This is an overloaded function.

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

See also contains() and indexOf().

[noexcept] QByteArray::const_reverse_iterator QByteArray::crbegin() const

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

See also begin(), rbegin(), and rend().

[noexcept] QByteArray::const_reverse_iterator QByteArray::crend() const

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

See also end(), rend(), and rbegin().

char *QByteArray::data()

Returns a pointer to the data stored in the byte array. The pointer can be used to access and modify the bytes that compose the array. The data is '\0'-terminated, i.e. the number of bytes you can access following the returned pointer is size() + 1, including the '\0' terminator.

Example:

QByteArray ba("Hello world");
char *data = ba.data();
while (*data) {
    cout << "[" << *data << "]" << endl;
    ++data;
}

The pointer remains valid as long as no detach happens and the QByteArray is not modified.

For read-only access, constData() is faster because it never causes a deep copy to occur.

This function is mostly useful to pass a byte array to a function that accepts a const char *.

The following example makes a copy of the char* returned by data(), but it will corrupt the heap and cause a crash because it does not allocate a byte for the '\0' at the end:

QString tmp = "test";
QByteArray text = tmp.toLocal8Bit();
char *data = new char[text.size()];
strcpy(data, text.data());
delete [] data;

This one allocates the correct amount of space:

QString tmp = "test";
QByteArray text = tmp.toLocal8Bit();
char *data = new char[text.size() + 1];
strcpy(data, text.data());
delete [] data;

Note: A QByteArray can store any byte values including '\0's, but most functions that take char * arguments assume that the data ends at the first '\0' they encounter.

See also constData() and operator[]().

[noexcept] const char *QByteArray::data() const

This is an overloaded function.

QByteArray::iterator QByteArray::end()

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

See also begin() and constEnd().

[noexcept] QByteArray::const_iterator QByteArray::end() const

This function overloads end().

[since 6.0] bool QByteArray::endsWith(QByteArrayView bv) const

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

Example:

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

This function was introduced in Qt 6.0.

See also startsWith() and last().

bool QByteArray::endsWith(char ch) const

This is an overloaded function.

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

[since 6.1] QByteArray::iterator QByteArray::erase(QByteArray::const_iterator first, QByteArray::const_iterator last)

Removes from the byte array the characters in the half-open range [ first , last ). Returns an iterator to the character referred to by last before the erase.

This function was introduced in Qt 6.1.

[since 6.5] QByteArray::iterator QByteArray::erase(QByteArray::const_iterator it)

This is an overloaded function.

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"

This function was introduced in Qt 6.5.

QByteArray &QByteArray::fill(char ch, qsizetype size = -1)

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:

QByteArray ba("Istambul");
ba.fill('o');
// ba == "oooooooo"

ba.fill('X', 2);
// ba == "XX"

See also resize().

[static] QByteArray QByteArray::fromBase64(const QByteArray &base64, QByteArray::Base64Options options = Base64Encoding)

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:

QByteArray 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.

See also toBase64() and fromBase64Encoding().

[static] QByteArray QByteArray::fromCFData(CFDataRef data)

Constructs a new QByteArray containing a copy of the CFData data.

See also fromRawCFData(), fromRawData(), toRawCFData(), and toCFData().

[static, since 6.5] QByteArray QByteArray::fromEcmaUint8Array(emscripten::val uint8array)

Constructs a new QByteArray containing a copy of the Uint8Array uint8array.

This function transfers data from a JavaScript data buffer - which is not addressable from C++ code - to heap memory owned by a QByteArray. The Uint8Array can be released once this function returns and a copy has been made.

The uint8array argument must an emscripten::val referencing an Uint8Array object, e.g. obtained from a global JavaScript variable:

emscripten::val uint8array = emscripten::val::global("g_uint8array");
QByteArray byteArray = QByteArray::fromEcmaUint8Array(uint8array);

This function returns a null QByteArray if the size of the Uint8Array exceeds the maximum capacity of QByteArray, or if the uint8array argument is not of the Uint8Array type.

This function was introduced in Qt 6.5.

See also toEcmaUint8Array().

[static] QByteArray QByteArray::fromHex(const QByteArray &hexEncoded)

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:

QByteArray text = QByteArray::fromHex("517420697320677265617421");
text.data();            // returns "Qt is great!"

See also toHex().

[static] QByteArray QByteArray::fromNSData(const NSData *data)

Constructs a new QByteArray containing a copy of the NSData data.

See also fromRawNSData(), fromRawData(), toNSData(), and toRawNSData().

[static] QByteArray QByteArray::fromPercentEncoding(const QByteArray &input, char percent = '%')

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:

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

See also percentDecoded().

[static] QByteArray QByteArray::fromRawCFData(CFDataRef data)

Constructs a QByteArray that uses the bytes of the CFData data.

The data's bytes are not copied.

The caller guarantees that the CFData will not be deleted or modified as long as this QByteArray object exists.

See also fromCFData(), fromRawData(), toRawCFData(), and toCFData().

[static] QByteArray QByteArray::fromRawData(const char *data, qsizetype size)

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:

 static const char mydata[] = {
    '\x00', '\x00', '\x03', '\x84', '\x78', '\x9c', '\x3b', '\x76',
    '\xec', '\x18', '\xc3', '\x31', '\x0a', '\xf1', '\xcc', '\x99',
    ...
    '\x6d', '\x5b'
};

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

See also setRawData(), data(), and constData().

[static] QByteArray QByteArray::fromRawNSData(const NSData *data)

Constructs a QByteArray that uses the bytes of the NSData data.

The data's bytes are not copied.

The caller guarantees that the NSData will not be deleted or modified as long as this QByteArray object exists.

See also fromNSData(), fromRawData(), toRawNSData(), and toNSData().

[static] QByteArray QByteArray::fromStdString(const std::string &str)

Returns a copy of the str string as a QByteArray.

See also toStdString() and QString::fromStdString().

char &QByteArray::front()

Returns a reference to the first byte in the byte array. Same as operator[](0).

This function is provided for STL compatibility.

See also back(), at(), and operator[]().

char QByteArray::front() const

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

This function is provided for STL compatibility.

See also back(), at(), and operator[]().

[since 6.0] qsizetype QByteArray::indexOf(QByteArrayView bv, qsizetype from = 0) const

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:

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

This function was introduced in Qt 6.0.

See also lastIndexOf(), contains(), and count().

qsizetype QByteArray::indexOf(char ch, qsizetype from = 0) const

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:

QByteArray ba("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() and contains().

[since 6.0] QByteArray &QByteArray::insert(qsizetype i, QByteArrayView data)

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

Example:

QByteArray ba("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.

This function was introduced in Qt 6.0.

See also append(), prepend(), replace(), and remove().

QByteArray &QByteArray::insert(qsizetype i, const QByteArray &data)

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(), and remove().

QByteArray &QByteArray::insert(qsizetype i, const char *s)

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(), and remove().

QByteArray &QByteArray::insert(qsizetype i, char ch)

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.

QByteArray &QByteArray::insert(qsizetype i, const char *data, qsizetype len)

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.

QByteArray &QByteArray::insert(qsizetype i, qsizetype count, char ch)

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.

[noexcept] bool QByteArray::isEmpty() const

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().

bool QByteArray::isLower() const

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() and toLower().

[noexcept] bool QByteArray::isNull() const

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().

bool QByteArray::isUpper() const

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() and toUpper().

[noexcept, since 6.3] bool QByteArray::isValidUtf8() const

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

This function was introduced in Qt 6.3.

[since 6.0] qsizetype QByteArray::lastIndexOf(QByteArrayView bv, qsizetype from) const

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:

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

This function was introduced in Qt 6.0.

See also indexOf(), contains(), and count().

[since 6.2] qsizetype QByteArray::lastIndexOf(QByteArrayView bv) const

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:

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

This function was introduced in Qt 6.2.

See also indexOf(), contains(), and count().

qsizetype QByteArray::lastIndexOf(char ch, qsizetype from = -1) const

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:

QByteArray ba("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() and contains().

QByteArray QByteArray::leftJustified(qsizetype width, char fill = ' ', bool truncate = false) const

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:

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

See also rightJustified().

[noexcept] qsizetype QByteArray::length() const

Same as size().

[static] QByteArray QByteArray::number(int n, int base = 10)

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:

int n = 63;
QByteArray::number(n);              // returns "63"
QByteArray::number(n, 16);          // returns "3f"
QByteArray::number(n, 16).toUpper();  // returns "3F"

See also setNum() and toInt().

[static] QByteArray QByteArray::number(long n, int base = 10)

This is an overloaded function.

See also toLong().

[static] QByteArray QByteArray::number(qlonglong n, int base = 10)

This is an overloaded function.

See also toLongLong().

[static] QByteArray QByteArray::number(qulonglong n, int base = 10)

This is an overloaded function.

See also toULongLong().

[static] QByteArray QByteArray::number(uint n, int base = 10)

This is an overloaded function.

See also toUInt().

[static] QByteArray QByteArray::number(ulong n, int base = 10)

This is an overloaded function.

See also toULong().

[static] QByteArray QByteArray::number(double n, char format = 'g', int precision = 6)

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 QString::number(double, char, int). For example:

QByteArray ba = QByteArray::number(12.3456, 'E', 3);
// ba == 1.235E+01

See also toDouble() and QLocale::FloatingPointPrecisionOption.

[since 6.4] QByteArray QByteArray::percentDecoded(char percent = '%') const

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:

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

This function was introduced in Qt 6.4.

See also toPercentEncoding() and QUrl::fromPercentEncoding().

QByteArray &QByteArray::prepend(QByteArrayView ba)

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:

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

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

See also append() and insert().

QByteArray &QByteArray::prepend(char ch)

This is an overloaded function.

Prepends the byte ch to this byte array.

QByteArray &QByteArray::prepend(const QByteArray &ba)

This is an overloaded function.

Prepends ba to this byte array.

QByteArray &QByteArray::prepend(const char *str)

This is an overloaded function.

Prepends the '\0'-terminated string str to this byte array.

QByteArray &QByteArray::prepend(const char *str, qsizetype len)

This is an overloaded function.

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

QByteArray &QByteArray::prepend(qsizetype count, char ch)

This is an overloaded function.

Prepends count copies of byte ch to this byte array.

void QByteArray::push_back(const QByteArray &other)

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

[since 6.0] void QByteArray::push_back(QByteArrayView str)

This is an overloaded function.

Same as append(str).

This function was introduced in Qt 6.0.

void QByteArray::push_back(char ch)

This is an overloaded function.

Same as append(ch).

void QByteArray::push_back(const char *str)

This is an overloaded function.

Same as append(str).

void QByteArray::push_front(const QByteArray &other)

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

[since 6.0] void QByteArray::push_front(QByteArrayView str)

This is an overloaded function.

Same as prepend(str).

This function was introduced in Qt 6.0.

void QByteArray::push_front(char ch)

This is an overloaded function.

Same as prepend(ch).

void QByteArray::push_front(const char *str)

This is an overloaded function.

Same as prepend(str).

QByteArray::reverse_iterator QByteArray::rbegin()

Returns a STL-style reverse iterator pointing to the first byte in the byte-array, in reverse order.

See also begin(), crbegin(), and rend().

[noexcept] QByteArray::const_reverse_iterator QByteArray::rbegin() const

This is an overloaded function.

QByteArray &QByteArray::remove(qsizetype pos, qsizetype len)

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:

QByteArray ba("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(), and squeeze().

[since 6.5] QByteArray &QByteArray::removeAt(qsizetype pos)

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

This function was introduced in Qt 6.5.

See also remove().

[since 6.5] QByteArray &QByteArray::removeFirst()

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

This function was introduced in Qt 6.5.

See also remove().

[since 6.1] template <typename Predicate> QByteArray &QByteArray::removeIf(Predicate pred)

Removes all bytes for which the predicate pred returns true from the byte array. Returns a reference to the byte array.

This function was introduced in Qt 6.1.

See also remove().

[since 6.5] QByteArray &QByteArray::removeLast()

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

This function was introduced in Qt 6.5.

See also remove().

QByteArray::reverse_iterator QByteArray::rend()

Returns a STL-style reverse iterator pointing just after the last byte in the byte-array, in reverse order.

See also end(), crend(), and rbegin().

[noexcept] QByteArray::const_reverse_iterator QByteArray::rend() const

This is an overloaded function.

QByteArray QByteArray::repeated(qsizetype times) const

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:

QByteArray ba("ab");
ba.repeated(4);             // returns "abababab"

QByteArray &QByteArray::replace(qsizetype pos, qsizetype len, QByteArrayView after)

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

Example:

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

See also insert() and remove().

[since 6.0] QByteArray &QByteArray::replace(QByteArrayView before, QByteArrayView after)

This is an overloaded function.

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

Example:

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

This function was introduced in Qt 6.0.

QByteArray &QByteArray::replace(char before, QByteArrayView after)

This is an overloaded function.

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

QByteArray &QByteArray::replace(char before, char after)

This is an overloaded function.

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

QByteArray &QByteArray::replace(const char *before, qsizetype bsize, const char *after, qsizetype asize)

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.

QByteArray &QByteArray::replace(qsizetype pos, qsizetype len, const char *after, qsizetype alen)

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.

void QByteArray::reserve(qsizetype size)

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.

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() and capacity().

void QByteArray::resize(qsizetype size)

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.

See also size(), truncate(), and squeeze().

[since 6.4] void QByteArray::resize(qsizetype newSize, char c)

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.

This function was introduced in Qt 6.4.

See also size(), truncate(), and squeeze().

[since 6.8] void QByteArray::resizeForOverwrite(qsizetype size)

Resizes the byte array to size bytes. If the size of the byte array grows, the new bytes are uninitialized.

The behavior is identical to resize(size).

This function was introduced in Qt 6.8.

See also resize().

QByteArray QByteArray::rightJustified(qsizetype width, char fill = ' ', bool truncate = false) const

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:

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

See also leftJustified().

QByteArray &QByteArray::setNum(int n, int base = 10)

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:

QByteArray ba;
int n = 63;
ba.setNum(n);           // ba == "63"
ba.setNum(n, 16);       // ba == "3f"

See also number() and toInt().

QByteArray &QByteArray::setNum(long n, int base = 10)

This is an overloaded function.

See also toLong().

QByteArray &QByteArray::setNum(qlonglong n, int base = 10)

This is an overloaded function.

See also toLongLong().

QByteArray &QByteArray::setNum(qulonglong n, int base = 10)

This is an overloaded function.

See also toULongLong().

QByteArray &QByteArray::setNum(short n, int base = 10)

This is an overloaded function.

See also toShort().

QByteArray &QByteArray::setNum(uint n, int base = 10)

This is an overloaded function.

See also toUInt().

QByteArray &QByteArray::setNum(ulong n, int base = 10)

This is an overloaded function.

See also toULong().

QByteArray &QByteArray::setNum(ushort n, int base = 10)

This is an overloaded function.

See also toUShort().

QByteArray &QByteArray::setNum(double n, char format = 'g', int precision = 6)

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 QString::number(double, char, int)), and returns a reference to this byte array.

See also toDouble() and QLocale::FloatingPointPrecisionOption.

QByteArray &QByteArray::setNum(float n, char format = 'g', int precision = 6)

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 QString::number(double, char, int)), and returns a reference to this byte array.

See also toFloat().

QByteArray &QByteArray::setRawData(const char *data, qsizetype size)

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(), and constData().

void QByteArray::shrink_to_fit()

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

QByteArray QByteArray::simplified() const

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:

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

See also trimmed(), QChar::SpecialCharacter, and Spacing Characters.

[noexcept] qsizetype QByteArray::size() const

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:

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

See also isEmpty() and resize().

[since 6.8] QByteArray &QByteArray::slice(qsizetype pos, qsizetype n)

Modifies this byte array to start at position pos, extending for n bytes, and returns a reference to this byte array.

Example:

QByteArray x = "Five pineapples"_ba;
x.slice(5);     // x == "pineapples"
x.slice(4, 3);  // x == "app"

This function was introduced in Qt 6.8.

See also sliced(), first(), last(), chopped(), chop(), and truncate().

[since 6.8] QByteArray &QByteArray::slice(qsizetype pos)

This is an overloaded function.

Modifies this byte array to start at position pos, extending to its end, and returns a reference to this byte array.

This function was introduced in Qt 6.8.

See also sliced(), first(), last(), chopped(), chop(), and truncate().

QList<QByteArray> QByteArray::split(char sep) const

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.

void QByteArray::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() and capacity().

[since 6.0] bool QByteArray::startsWith(QByteArrayView bv) const

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

Example:

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

This function was introduced in Qt 6.0.

See also endsWith() and first().

bool QByteArray::startsWith(char ch) const

This is an overloaded function.

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

[noexcept] void QByteArray::swap(QByteArray &other)

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

QByteArray QByteArray::toBase64(QByteArray::Base64Options options = Base64Encoding) const

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

QByteArray text("Qt is great!");
text.toBase64();        // returns "UXQgaXMgZ3JlYXQh"

QByteArray text("<p>Hello?</p>");
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().

CFDataRef QByteArray::toCFData() const

Creates a CFData from a QByteArray.

The caller owns the CFData object and is responsible for releasing it.

See also toRawCFData(), fromCFData(), fromRawCFData(), and fromRawData().

double QByteArray::toDouble(bool *ok = nullptr) const

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

QByteArray string("1234.56");
bool ok;
double a = string.toDouble(&ok);   // a == 1234.56, ok == true

string = "1234.56 Volt";
a = str.toDouble(&ok);             // a == 0, ok == false

This function ignores leading and trailing whitespace.

See also number().

[since 6.5] emscripten::val QByteArray::toEcmaUint8Array()

Creates a Uint8Array from a QByteArray.

This function transfers data from heap memory owned by a QByteArray to a JavaScript data buffer. The function allocates and copies into an ArrayBuffer, and returns a Uint8Array view to that buffer.

The JavaScript objects own a copy of the data, and this QByteArray can be safely deleted after the copy has been made.

QByteArray byteArray = "test";
emscripten::val uint8array = byteArray.toEcmaUint8Array();

This function was introduced in Qt 6.5.

See also toEcmaUint8Array().

float QByteArray::toFloat(bool *ok = nullptr) const

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

QByteArray string("1234.56");
bool ok;
float a = string.toFloat(&ok);    // a == 1234.56, ok == true

string = "1234.56 Volt";
a = str.toFloat(&ok);              // a == 0, ok == false

This function ignores leading and trailing whitespace.

See also number().

QByteArray QByteArray::toHex(char separator = '\0') const

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:

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

See also fromHex().

int QByteArray::toInt(bool *ok = nullptr, int base = 10) const

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

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

See also number().

long QByteArray::toLong(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

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

See also number().

qlonglong QByteArray::toLongLong(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

QByteArray QByteArray::toLower() const

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

Example:

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

See also isLower(), toUpper(), and Character Case.

NSData *QByteArray::toNSData() const

Creates a NSData from a QByteArray.

The NSData object is autoreleased.

See also fromNSData(), fromRawNSData(), fromRawData(), and toRawNSData().

QByteArray QByteArray::toPercentEncoding(const QByteArray &exclude = QByteArray(), const QByteArray &include = QByteArray(), char percent = '%') const

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() and QUrl::toPercentEncoding().

CFDataRef QByteArray::toRawCFData() const

Constructs a CFData that uses the bytes of the QByteArray.

The QByteArray's bytes are not copied.

The caller guarantees that the QByteArray will not be deleted or modified as long as this CFData object exists.

See also toCFData(), fromRawCFData(), fromCFData(), and fromRawData().

NSData *QByteArray::toRawNSData() const

Constructs a NSData that uses the bytes of the QByteArray.

The QByteArray's bytes are not copied.

The caller guarantees that the QByteArray will not be deleted or modified as long as this NSData object exists.

See also fromRawNSData(), fromNSData(), fromRawData(), and toNSData().

short QByteArray::toShort(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

std::string QByteArray::toStdString() const

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() and QString::toStdString().

uint QByteArray::toUInt(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

ulong QByteArray::toULong(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

qulonglong QByteArray::toULongLong(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

ushort QByteArray::toUShort(bool *ok = nullptr, int base = 10) const

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.

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 nullptr, failure is reported by setting *ok to false, and success by setting *ok to true.

See also number().

QByteArray QByteArray::toUpper() const

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

Example:

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

See also isUpper(), toLower(), and Character Case.

QByteArray QByteArray::trimmed() const

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

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:

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

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

See also simplified(), QChar::SpecialCharacter, and Spacing Characters.

void QByteArray::truncate(qsizetype pos)

Truncates the byte array at index position pos.

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

Example:

QByteArray ba("Stockholm");
ba.truncate(5);             // ba == "Stock"

See also chop(), resize(), and first().

QByteArray &QByteArray::operator+=(const QByteArray &ba)

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

Example:

QByteArray x("free");
QByteArray y("dom");
x += y;
// x == "freedom"

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.

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() and prepend().

QByteArray &QByteArray::operator+=(char ch)

This is an overloaded function.

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

QByteArray &QByteArray::operator+=(const char *str)

This is an overloaded function.

Appends the '\0'-terminated string str onto the end of this byte array and returns a reference to this byte array.

[noexcept] QByteArray &QByteArray::operator=(QByteArray &&other)

Move-assigns other to this QByteArray instance.

[noexcept] QByteArray &QByteArray::operator=(const QByteArray &other)

Assigns other to this byte array and returns a reference to this byte array.

QByteArray &QByteArray::operator=(const char *str)

This is an overloaded function.

Assigns str to this byte array.

str is assumed to point to a null-terminated string, and its length is determined dynamically.

char &QByteArray::operator[](qsizetype i)

Returns the byte at index position i as a modifiable reference.

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

Example:

QByteArray ba("Hello, world");
cout << ba[0]; // prints H
ba[7] = 'W';
// ba == "Hello, World"

See also at().

char QByteArray::operator[](qsizetype i) const

This is an overloaded function.

Same as at(i).