QByteArray Class

 QByteArray ba("Hello");

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

 for (qsizetype i = 0; i < ba.size(); ++i) {
     if (ba.at(i) >= 'a' && ba.at(i) <= 'f')
         cout << "Found character in range [a-f]" << Qt::endl;
 }

 QByteArray ba1("ca\0r\0t");
 ba1.size();                     // Returns 2.
 ba1.constData();                // Returns "ca" with terminating \0.

 QByteArray ba2("ca\0r\0t", 3);
 ba2.size();                     // Returns 3.
 ba2.constData();                // Returns "ca\0" with terminating \0.

 QByteArray ba3("ca\0r\0t", 4);
 ba3.size();                     // Returns 4.
 ba3.constData();                // Returns "ca\0r" with terminating \0.

 const char cart[] = {'c', 'a', '\0', 'r', '\0', 't'};
 QByteArray ba4(QByteArray::fromRawData(cart, 6));
 ba4.size();                     // Returns 6.
 ba4.constData();                // Returns "ca\0r\0t" without terminating \0.

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

 QByteArray ba("We must be <b>bold</b>, very <b>bold</b>");
 qsizetype j = 0;
 while ((j = ba.indexOf("<b>", j)) != -1) {
     cout << "Found <b> tag at index position " << j << Qt::endl;
     ++j;
 }

 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

Member Function Documentation

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.

This function was introduced in Qt 5.15.

See also toBase64().

Note: Use constData() instead in new code.

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().

[since 5.2] QByteArray::QByteArray(QByteArray &&other)

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

This function was introduced in Qt 5.2.

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=().

QByteArray::QByteArray(qsizetype size, char ch)

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

See also fill().

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()

Constructs an empty byte array.

See also isEmpty().

[since 5.2] QByteArray &QByteArray::operator=(QByteArray &&other)

Move-assigns other to this QByteArray instance.

This function was introduced in Qt 5.2.

QByteArray &QByteArray::operator=(const QByteArray &other)

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

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(char ch)

This is an overloaded function.

Appends the byte ch to this byte array.

[since 5.7] 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.

This function was introduced in Qt 5.7.

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(QByteArrayView data)

This is an overloaded function.

Appends data to this byte array.

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[]().

[since 5.10] char QByteArray::back() const

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.

This function was introduced in Qt 5.10.

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

[since 5.10] 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.

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

This function was introduced in Qt 5.10.

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

QByteArray::iterator QByteArray::begin()

Returns an 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 constBegin() and end().

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().

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() and squeeze().

[since 5.0] QByteArray::const_iterator QByteArray::cbegin() const

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.

This function was introduced in Qt 5.0.

See also begin() and cend().

[since 5.0] QByteArray::const_iterator QByteArray::cend() const

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.

This function was introduced in Qt 5.0.

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().

[since 5.10] QByteArray QByteArray::chopped(qsizetype len) const

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

Note: The behavior is undefined if len is negative or greater than size().

This function was introduced in Qt 5.10.

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

void QByteArray::clear()

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

See also resize() and isNull().

[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.

QByteArray::const_iterator QByteArray::constBegin() const

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() and constEnd().

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().

QByteArray::const_iterator QByteArray::constEnd() const

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 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().

qsizetype QByteArray::count() const

This is an overloaded function.

Same as size().

[since 5.6] 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.

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

This function was introduced in Qt 5.6.

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

[since 5.6] 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.

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

This function was introduced in Qt 5.6.

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 << "]" << Qt::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[]().

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.

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

See also begin() and constEnd().

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.

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().

[since 6.0] QByteArray QByteArray::first(qsizetype n) const

Returns the first n bytes of the byte array.

Note: The behavior is undefined when n < 0 or n > size().

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(), and truncate().

[static, since 5.2] 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.

Note: The fromBase64Encoding() function is recommended in new code.

This function was introduced in Qt 5.2.

See also toBase64() and fromBase64Encoding().

[static, since 5.3] QByteArray QByteArray::fromCFData(CFDataRef data)

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

This function was introduced in Qt 5.3.

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

[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, since 5.3] QByteArray QByteArray::fromNSData(const NSData *data)

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

This function was introduced in Qt 5.3.

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

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

Returns a decoded copy of the URI/URL-style percent-encoded input. The percent parameter allows you to replace the '%' character for another (for instance, '_' or '=').

For example:

 QByteArray text = QByteArray::fromPercentEncoding("Qt%20is%20great%33");
 text.data();            // returns "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'.

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

[static, since 5.3] 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.

This function was introduced in Qt 5.3.

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);
 ...

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(), and constData().

[static, since 5.3] 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.

This function was introduced in Qt 5.3.

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

[static, since 5.4] QByteArray QByteArray::fromStdString(const std::string &str)

Returns a copy of the str string as a QByteArray.

This function was introduced in Qt 5.4.

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

[since 5.10] char QByteArray::front() const

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.

This function was introduced in Qt 5.10.

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

[since 5.10] 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.

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

This function was introduced in Qt 5.10.

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 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, 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().

[since 5.7] 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.

This function was introduced in Qt 5.7.

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.

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().

[since 5.12] bool QByteArray::isLower() const

Returns true if this byte array contains only lowercase ASCII letters, otherwise returns false.

This function was introduced in Qt 5.12.

See also isUpper() and toLower().

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().

[since 5.12] bool QByteArray::isUpper() const

Returns true if this byte array contains only ASCII uppercase letters, otherwise returns false.

This function was introduced in Qt 5.12.

See also isLower() and toUpper().

[since 6.0] QByteArray QByteArray::last(qsizetype n) const

Returns the last n bytes of the byte array.

Note: The behavior is undefined when n < 0 or n > size().

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(), and truncate().

[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 from 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

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.

This function was introduced in Qt 6.0.

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().

[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().

QByteArray QByteArray::left(qsizetype len) const

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().

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().

qsizetype QByteArray::length() const

Same as size().

QByteArray QByteArray::mid(qsizetype pos, qsizetype len = -1) const

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(), and truncate().

[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 representating 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"

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() and toInt().

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

This is an overloaded function.

See also toUInt().

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

This is an overloaded function.

See also toLong().

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

This is an overloaded function.

See also toULong().

[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(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.

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.

[since 5.7] QByteArray &QByteArray::prepend(qsizetype count, char ch)

This is an overloaded function.

Prepends count copies of byte ch to this byte array.

This function was introduced in Qt 5.7.

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(const QByteArray &ba)

This is an overloaded function.

Prepends ba to this byte array.

void QByteArray::push_back(const QByteArray &other)

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

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).

[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_front(const QByteArray &other)

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

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).

[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.

[since 5.6] QByteArray::reverse_iterator QByteArray::rbegin()

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

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

This function was introduced in Qt 5.6.

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

[since 5.6] QByteArray::const_reverse_iterator QByteArray::rbegin() const

This is an overloaded function.

This function was introduced in Qt 5.6.

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 6.1] 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 5.6] QByteArray::reverse_iterator QByteArray::rend()

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

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

This function was introduced in Qt 5.6.

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

[since 5.6] QByteArray::const_reverse_iterator QByteArray::rend() const

This is an overloaded function.

This function was introduced in Qt 5.6.

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().

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.

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(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.

[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, char after)

This is an overloaded function.

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

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.

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() 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.

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

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

QByteArray QByteArray::right(qsizetype len) const

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(), and truncate().

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"

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() and toInt().

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

This is an overloaded function.

See also toShort().

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

This is an overloaded function.

See also toUShort().

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

This is an overloaded function.

See also toUInt().

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

This is an overloaded function.

See also toLong().

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

This is an overloaded function.

See also toULong().

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(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 representating 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::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 representating 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::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().

[since 5.10] void QByteArray::shrink_to_fit()

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

This function was introduced in Qt 5.10.

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.

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 automaticall 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 6.0] QByteArray QByteArray::sliced(qsizetype pos, qsizetype n) const

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

Note: The behavior is undefined when pos < 0, n < 0, or pos + n > size().

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(), and truncate().

[since 6.0] QByteArray QByteArray::sliced(qsizetype pos) const

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.

Note: The behavior is undefined when pos < 0 or pos > size().

This function was introduced in Qt 6.0.

See also first(), last(), sliced(), 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.

void QByteArray::swap(QByteArray &other)

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

[since 5.2] 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.

This function was introduced in Qt 5.2.

See also fromBase64().

[since 5.3] CFDataRef QByteArray::toCFData() const

Creates a CFData from a QByteArray.

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

This function was introduced in Qt 5.3.

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

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().

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

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().

[since 5.9] 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"

This function was introduced in Qt 5.9.

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 "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

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.

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 "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

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.

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 "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.

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.

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.

[since 5.3] NSData *QByteArray::toNSData() const

Creates a NSData from a QByteArray.

The NSData object is autoreleased.

This function was introduced in Qt 5.3.

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(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().

[since 5.3] 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.

This function was introduced in Qt 5.3.

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

[since 5.3] 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.

This function was introduced in Qt 5.3.

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; otherwise, if it begins with "0", it is assumed to be octal; 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.

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.

See also number().

[since 5.4] 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.

This function was introduced in Qt 5.4.

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 "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.

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.

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 "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.

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.

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 "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.

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.

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; otherwise, if it begins with "0", it is assumed to be octal; 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.

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.

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().

bool QByteArray::operator!=(const QString &str) const

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 QString::fromUtf8(), QString::fromLatin1(), or QString::fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.

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.

bool QByteArray::operator<(const QString &str) const

Returns true if this byte array is lexically less than 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 QString::fromUtf8(), QString::fromLatin1(), or QString::fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.

bool QByteArray::operator<=(const QString &str) const

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.

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

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

This is an overloaded function.

Assigns str to this byte array.

bool QByteArray::operator==(const QString &str) const

Returns true if this byte array is 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 QString::fromUtf8(), QString::fromLatin1(), or QString::fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.

bool QByteArray::operator>(const QString &str) const

Returns true if this byte array is lexically greater than 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 QString::fromUtf8(), QString::fromLatin1(), or QString::fromLocal8Bit() explicitly if you want to convert the byte array to a QString before doing the comparison.

bool QByteArray::operator>=(const QString &str) const

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.

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

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).

 auto str = "hello"_qba;

 QByteArray ba = QByteArrayLiteral("byte array contents");