|  | Home · All Classes · Modules

# QByteArray Class Reference
[QtCore module]

The QByteArray class provides an array of bytes. More...

### Methods

- __init__ (self)
- __init__ (self, int size, str c)
- __init__ (self, QByteArray a)
- QByteArray append (self, QByteArray a)
- QByteArray append (self, QString s)
- str at (self, int i)
- int capacity (self)
- chop (self, int n)
- clear (self)
- bool contains (self, QByteArray a)
- int count (self, QByteArray a)
- int count (self)
- str data (self)
- bool endsWith (self, QByteArray a)
- QByteArray fill (self, str ch, int size = -1)
- int indexOf (self, QByteArray ba, int from = 0)
- int indexOf (self, QString str, int from = 0)
- QByteArray insert (self, int i, QByteArray a)
- QByteArray insert (self, int i, QString s)
- bool isEmpty (self)
- bool isNull (self)
- int lastIndexOf (self, QByteArray ba, int from = -1)
- int lastIndexOf (self, QString str, int from = -1)
- QByteArray left (self, int len)
- QByteArray leftJustified (self, int width, str fill = ' ', bool truncate = False)
- int length (self)
- QByteArray mid (self, int pos, int length = -1)
- QByteArray prepend (self, QByteArray a)
- push_back (self, QByteArray a)
- push_front (self, QByteArray a)
- QByteArray remove (self, int index, int len)
- QByteArray repeated (self, int times)
- QByteArray replace (self, int index, int len, QByteArray s)
- QByteArray replace (self, QByteArray before, QByteArray after)
- QByteArray replace (self, QString before, QByteArray after)
- reserve (self, int size)
- resize (self, int size)
- QByteArray right (self, int len)
- QByteArray rightJustified (self, int width, str fill = ' ', bool truncate = False)
- QByteArray setNum (self, int n, int base = 10)
- QByteArray setNum (self, float n, str format = 'g', int precision = 6)
- QByteArray setNum (self, int n, int base = 10)
- QByteArray setNum (self, int n, int base = 10)
- QByteArray simplified (self)
- int size (self)
- list-of-QByteArray split (self, str sep)
- squeeze (self)
- bool startsWith (self, QByteArray a)
- swap (self, QByteArray other)
- QByteArray toBase64 (self)
- (float, bool ok) toDouble (self)
- (float, bool ok) toFloat (self)
- QByteArray toHex (self)
- (int, bool ok) toInt (self, int base = 10)
- (int, bool ok) toLong (self, int base = 10)
- (int, bool ok) toLongLong (self, int base = 10)
- QByteArray toLower (self)
- QByteArray toPercentEncoding (self, QByteArray exclude = QByteArray(), QByteArray include = QByteArray(), str percent = '%')
- (int, bool ok) toShort (self, int base = 10)
- (int, bool ok) toUInt (self, int base = 10)
- (int, bool ok) toULong (self, int base = 10)
- (int, bool ok) toULongLong (self, int base = 10)
- QByteArray toUpper (self)
- (int, bool ok) toUShort (self, int base = 10)
- QByteArray trimmed (self)
- truncate (self, int pos)

### Static Methods

- QByteArray fromBase64 (QByteArray base64)
- QByteArray fromHex (QByteArray hexEncoded)
- QByteArray fromPercentEncoding (QByteArray input, str percent = '%')
- QByteArray fromRawData (str)
- QByteArray number (int n, int base = 10)
- QByteArray number (float n, str format = 'g', int precision = 6)
- QByteArray number (int n, int base = 10)
- QByteArray number (int n, int base = 10)

### Special Methods

- QByteArray __add__ (self, QByteArray a2)
- QString __add__ (self, QString s)
- int __contains__ (self, QByteArray a)
- bool __eq__ (self, QString s2)
- bool __eq__ (self, QByteArray a2)
- bool __ge__ (self, QString s2)
- bool __ge__ (self, QByteArray a2)
- str __getitem__ (self, int i)
- QByteArray __getitem__ (self, slice slice)
- bool __gt__ (self, QString s2)
- bool __gt__ (self, QByteArray a2)
- int __hash__ (self)
- QByteArray __iadd__ (self, QByteArray a)
- QByteArray __iadd__ (self, QString s)
- QByteArray __imul__ (self, int m)
- bool __le__ (self, QString s2)
- bool __le__ (self, QByteArray a2)
- __len__ (self)
- bool __lt__ (self, QString s2)
- bool __lt__ (self, QByteArray a2)
- QByteArray __mul__ (self, int m)
- bool __ne__ (self, QString s2)
- bool __ne__ (self, QByteArray a2)
- str __repr__ (self)
- str __str__ (self)

## Detailed Description

This class can be pickled.

A Python string object may be used whenever a QByteArray is expected.

The QByteArray class provides an array of bytes.

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

In addition to QByteArray, Qt also provides the QString class to store string data. For most purposes, QString is the class you want to use. It stores 16-bit Unicode characters, making it easy to store non-ASCII/non-Latin-1 characters in your application. Furthermore, QString is used throughout in the Qt API. The two main cases where QByteArray is appropriate are when you need to store raw binary data, and when memory conservation is critical (e.g., with Qt for Embedded Linux).

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

     QByteArray ba("Hello");

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

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

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

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

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

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

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

To extract many bytes at a time, use left(), right(), or mid().

A QByteArray can embed '\0' bytes. The size() function always returns the size of the whole array, including embedded '\0' bytes. If you want to obtain the length of the data up to and excluding the first '\0' character, call qstrlen() on the byte array.

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

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

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

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

The replace() and remove() functions' first two arguments are the position from which to start erasing and the number of bytes that should be erased.

When you append() data to a non-empty array, the array will be reallocated and the new data copied to it. You can avoid this behavior by calling reserve(), which preallocates a certain amount of memory. You can also call capacity() to find out how much memory QByteArray actually allocated. Data appended to an empty array is not copied.

A frequent requirement is to remove whitespace characters from a byte array ('\n', '\t', ' ', etc.). If you want to remove whitespace from both ends of a QByteArray, use trimmed(). If you want to remove whitespace from both ends and replace multiple consecutive whitespaces with a single space character within the byte array, use simplified().

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

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

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

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

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

     QByteArray().isNull();          // returns true
     QByteArray().isEmpty();         // returns true

     QByteArray("").isNull();        // returns false
     QByteArray("").isEmpty();       // returns true

     QByteArray("abc").isNull();     // returns false
     QByteArray("abc").isEmpty();    // returns false

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

### Notes on Locale

#### Number-String Conversions

Functions that perform conversions between numeric data types and strings are performed in the C locale, irrespective of the user's locale settings. Use QString to perform locale-aware conversions between numbers and strings.

#### 8-bit Character Comparisons

In QByteArray, the notion of uppercase and lowercase and of which character is greater than or less than another character is locale dependent. This affects functions that support a case insensitive option or that compare or lowercase or uppercase their arguments. Case insensitive operations and comparisons will be accurate if both strings contain only ASCII characters. (If `$LC_CTYPE` is set, most Unix systems do "the right thing".) Functions that this affects include contains(), indexOf(), lastIndexOf(), operator<(), operator<=(), operator>(), operator>=(), toLower() and toUpper().

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

## Method Documentation

### QByteArray.__init__ (self)

Constructs an empty byte array.

See also isEmpty().

### QByteArray.__init__ (self, int size, str c)

Constructs a byte array initialized with the string str.

QByteArray makes a deep copy of the string data.

### QByteArray.__init__ (self, QByteArray a)

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

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

QByteArray makes a deep copy of the string data.

See also fromRawData().

### QByteArray QByteArray.append (self, QByteArray a)

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 this is an empty QByteArray, then this 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 this is not an empty QByteArray, 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 operator+=(), prepend(), and insert().

### QByteArray QByteArray.append (self, QString s)

This is an overloaded function.

Appends the string str to this byte array. The Unicode data is converted into 8-bit characters using QString.toAscii().

If the QString contains non-ASCII Unicode characters, using this function can lead to loss of information. You can disable this function by defining `QT_NO_CAST_TO_ASCII` when you compile your applications. You then need to call QString.toAscii() (or QString.toLatin1() or QString.toUtf8() or QString.toLocal8Bit()) explicitly if you want to convert the data to `const char *`.

### str QByteArray.at (self, int i)

Returns the character 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[]().

### int QByteArray.capacity (self)

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().

### QByteArray.chop (self, int 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 left().

### QByteArray.clear (self)

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

See also resize() and isEmpty().

### bool QByteArray.contains (self, QByteArray a)

Returns true if the byte array contains an occurrence of the byte array ba; otherwise returns false.

See also indexOf() and count().

### int QByteArray.count (self, QByteArray a)

Returns the number of (potentially overlapping) occurrences of byte array ba in this byte array.

See also contains() and indexOf().

### int QByteArray.count (self)

This is an overloaded function.

Returns the number of (potentially overlapping) occurrences of string str in the byte array.

### str QByteArray.data (self)

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 in the returned character string is size() + 1 for 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 the byte array isn't reallocated or destroyed. 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[]().

### bool QByteArray.endsWith (self, QByteArray a)

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

Example:

     QByteArray url("http://qt.nokia.com/index.html");
     if (url.endsWith(".html"))
         ...

See also startsWith() and right().

### QByteArray QByteArray.fill (self, str ch, int size = -1)

Sets every byte in the byte array to character 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().

### QByteArray QByteArray.fromBase64 (QByteArray base64)

Returns a decoded copy of the Base64 array base64. 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.fromBase64("UXQgaXMgZ3JlYXQh");
     text.data();            // returns "Qt is great!"

The algorithm used to decode Base64-encoded data is defined in RFC 2045.

See also toBase64().

### QByteArray QByteArray.fromHex (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().

### QByteArray QByteArray.fromPercentEncoding (QByteArray input, str 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!"

This function was introduced in Qt 4.4.

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

### QByteArray QByteArray.fromRawData (str)

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[] = {
         0x00, 0x00, 0x03, 0x84, 0x78, 0x9c, 0x3b, 0x76,
         0xec, 0x18, 0xc3, 0x31, 0x0a, 0xf1, 0xcc, 0x99,
         ...
         0x6d, 0x5b
     };

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

Warning: A byte array created with fromRawData() is not null-terminated, unless the raw data contains a 0 character 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().

### int QByteArray.indexOf (self, QByteArray ba, int from = 0)

Returns the index position of the first occurrence of the byte array ba in this byte array, searching forward from index position from. Returns -1 if ba could not be found.

Example:

     QByteArray x("sticky question");
     QByteArray 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

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

### int QByteArray.indexOf (self, QString str, int from = 0)

This is an overloaded function.

Returns the index position of the first occurrence of the string str in the byte array, searching forward from index position from. Returns -1 if str could not be found.

The Unicode data is converted into 8-bit characters using QString.toAscii().

If the QString contains non-ASCII Unicode characters, using this function can lead to loss of information. You can disable this function by defining `QT_NO_CAST_TO_ASCII` when you compile your applications. You then need to call QString.toAscii() (or QString.toLatin1() or QString.toUtf8() or QString.toLocal8Bit()) explicitly if you want to convert the data to `const char *`.

### QByteArray QByteArray.insert (self, int i, QByteArray a)

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

Example:

     QByteArray ba("Meal");
     ba.insert(1, QByteArray("ontr"));
     // ba == "Montreal"

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

### QByteArray QByteArray.insert (self, int i, QString s)

This is an overloaded function.

Inserts the string str at index position i in the byte array. The Unicode data is converted into 8-bit characters using QString.toAscii().

If i is greater than size(), the array is first extended using resize().

If the QString contains non-ASCII Unicode characters, using this function can lead to loss of information. You can disable this function by defining `QT_NO_CAST_TO_ASCII` when you compile your applications. You then need to call QString.toAscii() (or QString.toLatin1() or QString.toUtf8() or QString.toLocal8Bit()) explicitly if you want to convert the data to `const char *`.

### bool QByteArray.isEmpty (self)

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.isNull (self)

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().

### int QByteArray.lastIndexOf (self, QByteArray ba, int from = -1)

Returns the index position of the last occurrence of the byte array ba in this byte array, searching backward from index position from. If from is -1 (the default), the search starts at the last byte. Returns -1 if ba could not be found.

Example:

     QByteArray x("crazy azimuths");
     QByteArray 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

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

### int QByteArray.lastIndexOf (self, QString str, int from = -1)

This is an overloaded function.

Returns the index position of the last occurrence of the string str in the byte array, searching backward from index position from. If from is -1 (the default), the search starts at the last (size() - 1) byte. Returns -1 if str could not be found.

The Unicode data is converted into 8-bit characters using QString.toAscii().

If the QString contains non-ASCII Unicode characters, using this function can lead to loss of information. You can disable this function by defining `QT_NO_CAST_TO_ASCII` when you compile your applications. You then need to call QString.toAscii() (or QString.toLatin1() or QString.toUtf8() or QString.toLocal8Bit()) explicitly if you want to convert the data to `const char *`.

### QByteArray QByteArray.left (self, int len)

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

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

Example:

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

See also right(), mid(), startsWith(), and truncate().

### QByteArray QByteArray.leftJustified (self, int width, str fill = ' ', bool truncate = False)

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

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().

### int QByteArray.length (self)

Same as size().

### QByteArray QByteArray.mid (self, int pos, int length = -1)

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

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.

Example:

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

See also left() and right().

### QByteArray QByteArray.number (int n, int base = 10)

Returns a byte array containing the string equivalent of the number n to base base (10 by default). The base can be any value between 2 and 36.

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 irrespective of the user's locale.

See also setNum() and toInt().

### QByteArray QByteArray.number (float n, str format = 'g', int precision = 6)

This is an overloaded function.

See also toUInt().

### QByteArray QByteArray.number (int n, int base = 10)

This is an overloaded function.

See also toLongLong().

### QByteArray QByteArray.number (int n, int base = 10)

This is an overloaded function.

See also toULongLong().

### QByteArray QByteArray.prepend (self, QByteArray a)

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

Example:

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

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

Note: QByteArray is an implicitly shared class. Consequently, if this is an empty QByteArray, then this 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 this is not an empty QByteArray, a deep copy of the data is performed, taking linear time.

See also append() and insert().

### QByteArray.push_back (self, QByteArray a)

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

### QByteArray.push_front (self, QByteArray a)

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

### QByteArray QByteArray.remove (self, int index, int 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"

See also insert() and replace().

### QByteArray QByteArray.repeated (self, int times)

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"

This function was introduced in Qt 4.5.

### QByteArray QByteArray.replace (self, int index, int len, QByteArray s)

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 (self, QByteArray before, QByteArray after)

This is an overloaded function.

Replaces len bytes from index position pos with the zero terminated string after.

Notice: this can change the length of the byte array.

### QByteArray QByteArray.replace (self, QString before, QByteArray after)

This is an overloaded function.

Replaces len bytes from index position pos with alen bytes from the string after. after is allowed to have '\0' characters.

This function was introduced in Qt 4.7.

### QByteArray.reserve (self, int 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 size is an underestimate, the worst that will happen is that the QByteArray will be a bit slower.

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 change the size of the byte array, call resize().

See also squeeze() and capacity().

### QByteArray.resize (self, int 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 are removed from the end.

See also size() and truncate().

### QByteArray QByteArray.right (self, int len)

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

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

Example:

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

See also endsWith(), left(), and mid().

### QByteArray QByteArray.rightJustified (self, int width, str fill = ' ', bool truncate = False)

Returns a byte array of size width that contains the fill character 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 (self, int n, int base = 10)

Sets the byte array to the printed value of n in base base (10 by default) and returns a reference to the byte array. The base can be any value between 2 and 36.

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 irrespective of the user's locale.

See also number() and toInt().

### QByteArray QByteArray.setNum (self, float n, str format = 'g', int precision = 6)

This is an overloaded function.

See also toUInt().

### QByteArray QByteArray.setNum (self, int n, int base = 10)

This is an overloaded function.

See also toShort().

### QByteArray QByteArray.setNum (self, int n, int base = 10)

This is an overloaded function.

See also toUShort().

### QByteArray QByteArray.simplified (self)

Returns a byte array that has whitespace removed from the start and the end, and which has each sequence of internal whitespace replaced with a single space.

Whitespace means any character for which the standard C++ isspace() function returns true. This includes the ASCII characters '\t', '\n', '\v', '\f', '\r', and ' '.

Example:

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

See also trimmed().

### int QByteArray.size (self)

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 null-termination character then QByteArray doesn't add it automaticall unless the deep copy is created.

Example:

     QByteArray ba("Hello");
     int 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().

### list-of-QByteArray QByteArray.split (self, str sep)

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.

### QByteArray.squeeze (self)

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().

### bool QByteArray.startsWith (self, QByteArray a)

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

Example:

     QByteArray url("ftp://ftp.qt.nokia.com/");
     if (url.startsWith("ftp:"))
         ...

See also endsWith() and left().

### QByteArray.swap (self, QByteArray other)

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

This function was introduced in Qt 4.8.

### QByteArray QByteArray.toBase64 (self)

Returns a copy of the byte array, encoded as Base64.

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

The algorithm used to encode Base64-encoded data is defined in RFC 2045.

See also fromBase64().

### (float, bool ok) QByteArray.toDouble (self)

Returns the byte array converted to a `double` value.

Returns 0.0 if the conversion fails.

If ok is not 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

     QByteArray string("1234.56");
     double a = string.toDouble();   // a == 1234.56

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### (float, bool ok) QByteArray.toFloat (self)

Returns the byte array converted to a `float` value.

Returns 0.0 if the conversion fails.

If ok is not 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### QByteArray QByteArray.toHex (self)

Returns a hex encoded copy of the byte array. The hex encoding uses the numbers 0-9 and the letters a-f.

See also fromHex().

### (int, bool ok) QByteArray.toInt (self, int base = 10)

Returns the byte array converted to an `int` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set 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, irrespective of the user's locale.

See also number().

### (int, bool ok) QByteArray.toLong (self, int base = 10)

Returns the byte array converted to a `long` int using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set 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, irrespective of the user's locale.

This function was introduced in Qt 4.1.

See also number().

### (int, bool ok) QByteArray.toLongLong (self, int base = 10)

Returns the byte array converted to a `long long` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### QByteArray QByteArray.toLower (self)

Returns a lowercase copy of the byte array. The bytearray is interpreted as a Latin-1 encoded string.

Example:

     QByteArray x("Qt by NOKIA");
     QByteArray y = x.toLower();
     // y == "qt by nokia"

See also toUpper() and 8-bit Character Comparisons.

### QByteArray QByteArray.toPercentEncoding (self, QByteArray exclude = QByteArray(), QByteArray include = QByteArray(), str percent = '%')

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 characters that are not one of the following:

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

To prevent characters from being encoded pass them to exclude. To force characters 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.

This function was introduced in Qt 4.4.

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

### (int, bool ok) QByteArray.toShort (self, int base = 10)

Returns the byte array converted to a `short` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### (int, bool ok) QByteArray.toUInt (self, int base = 10)

Returns the byte array converted to an `unsigned int` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### (int, bool ok) QByteArray.toULong (self, int base = 10)

Returns the byte array converted to an `unsigned long int` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

This function was introduced in Qt 4.1.

See also number().

### (int, bool ok) QByteArray.toULongLong (self, int base = 10)

Returns the byte array converted to an `unsigned long long` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### QByteArray QByteArray.toUpper (self)

Returns an uppercase copy of the byte array. The bytearray is interpreted as a Latin-1 encoded string.

Example:

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

See also toLower() and 8-bit Character Comparisons.

### (int, bool ok) QByteArray.toUShort (self, int base = 10)

Returns the byte array converted to an `unsigned short` using base base, which is 10 by default and must be between 2 and 36, or 0.

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; 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 0: if a conversion error occurs, *ok is set to false; otherwise *ok is set to true.

Note: The conversion of the number is performed in the default C locale, irrespective of the user's locale.

See also number().

### QByteArray QByteArray.trimmed (self)

Returns a byte array that has whitespace removed from the start and the end.

Whitespace means any character for which the standard C++ isspace() function returns true. This includes the ASCII characters '\t', '\n', '\v', '\f', '\r', and ' '.

Example:

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

Unlike simplified(), trimmed() leaves internal whitespace alone.

See also simplified().

### QByteArray.truncate (self, int 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 left().

### QByteArray QByteArray.__add__ (self, QByteArray a2)

### QString QByteArray.__add__ (self, QString s)

### int QByteArray.__contains__ (self, QByteArray a)

### bool QByteArray.__eq__ (self, QString s2)

### bool QByteArray.__eq__ (self, QByteArray a2)

### bool QByteArray.__ge__ (self, QString s2)

### bool QByteArray.__ge__ (self, QByteArray a2)

### str QByteArray.__getitem__ (self, int i)

### QByteArray QByteArray.__getitem__ (self, slice slice)

### bool QByteArray.__gt__ (self, QString s2)

### bool QByteArray.__gt__ (self, QByteArray a2)

### int QByteArray.__hash__ (self)

### QByteArray QByteArray.__iadd__ (self, QByteArray a)

### QByteArray QByteArray.__iadd__ (self, QString s)

### QByteArray QByteArray.__imul__ (self, int m)

### bool QByteArray.__le__ (self, QString s2)

### bool QByteArray.__le__ (self, QByteArray a2)

### QByteArray.__len__ (self)

### bool QByteArray.__lt__ (self, QString s2)

### bool QByteArray.__lt__ (self, QByteArray a2)

### QByteArray QByteArray.__mul__ (self, int m)

### bool QByteArray.__ne__ (self, QString s2)

### bool QByteArray.__ne__ (self, QByteArray a2)

### str QByteArray.__repr__ (self)

### str QByteArray.__str__ (self)