QTextStream Class Reference

Constructs a QTextStream. Before you can use it for reading or writing, you must assign a device or a string.

See also setDevice() and setString().

Constructs a QTextStream that operates on device.

Constructs a QTextStream that operates on fileHandle, using openMode to define the open mode. Internally, a QFile is created to handle the FILE pointer.

This constructor is useful for working directly with the common FILE based input and output streams: stdin, stdout and stderr. Example:

Constructs a QTextStream that operates on string, using openMode to define the open mode.

Constructs a QTextStream that operates on array, using openMode to define the open mode. Internally, the array is wrapped by a QBuffer.

Constructs a QTextStream that operates on array, using openMode to define the open mode. The array is accessed as read-only, regardless of the values in openMode.

This constructor is convenient for working on constant strings. Example:

Destroys the QTextStream.

If the stream operates on a device, flush() will be called implicitly. Otherwise, the device is unaffected.

Returns true if there is no more data to be read from the QTextStream; otherwise returns false. This is similar to, but not the same as calling QIODevice::atEnd(), as QTextStream also takes into account its internal Unicode buffer.

Returns true if automatic Unicode detection is enabled, otherwise returns false. Automatic Unicode detection is enabled by default.

See also setAutoDetectUnicode() and setCodec().

Returns the codec that is current assigned to the stream.

See also setCodec(), setAutoDetectUnicode(), and locale().

Returns the current device associated with the QTextStream, or 0 if no device has been assigned.

See also setDevice() and string().

Returns the current field alignment.

See also setFieldAlignment() and fieldWidth().

Returns the current field width.

See also setFieldWidth().

Flushes any buffered data waiting to be written to the device.

If QTextStream operates on a string, this function does nothing.

Returns true if QTextStream is set to generate the UTF BOM (Byte Order Mark) when using a UTF codec; otherwise returns false. UTF BOM generation is set to false by default.

See also setGenerateByteOrderMark().

Returns the current base of integers. 0 means that the base is detected when reading, or 10 (decimal) when generating numbers.

See also setIntegerBase(), QString::number(), and numberFlags().

Returns the locale for this stream. The default locale is C.

See also setLocale().

Returns the current number flags.

See also setNumberFlags(), integerBase(), and realNumberNotation().

Returns the current pad character.

See also setPadChar() and setFieldWidth().

Returns the device position corresponding to the current position of the stream, or -1 if an error occurs (e.g., if there is no device or string, or if there's a device error).

Because QTextStream is buffered, this function may have to seek the device to reconstruct a valid device position. This operation can be expensive, so you may want to avoid calling this function in a tight loop.

See also seek().

Reads at most maxlen characters from the stream, and returns the data read as a QString.

See also readAll(), readLine(), and QIODevice::read().

Reads the entire content of the stream, and returns it as a QString. Avoid this function when working on large files, as it will consume a significant amount of memory.

Calling readLine() is better if you do not know how much data is available.

See also readLine().

Reads one line of text from the stream, and returns it as a QString. The maximum allowed line length is set to maxlen. If the stream contains lines longer than this, then the lines will be split after maxlen characters and returned in parts.

If maxlen is 0, the lines can be of any length. A common value for maxlen is 75.

The returned line has no trailing end-of-line characters ("\n" or "\r\n"), so calling QString::trimmed() is unnecessary.

If the stream has read to the end of the file, readLine() will return a null QString. For strings, or for devices that support it, you can explicitly test for the end of the stream using atEnd().

See also readAll() and QIODevice::readLine().

Returns the current real number notation.

See also setRealNumberNotation(), realNumberPrecision(), numberFlags(), and integerBase().

Returns the current real number precision, or the number of fraction digits QTextStream will write when generating real numbers.

See also setRealNumberPrecision(), setRealNumberNotation(), realNumberNotation(), numberFlags(), and integerBase().

Resets QTextStream's formatting options, bringing it back to its original constructed state. The device, string and any buffered data is left untouched.

Resets the status of the text stream.

See also QTextStream::Status, status(), and setStatus().

Seeks to the position pos in the device. Returns true on success; otherwise returns false.

If enabled is true, QTextStream will attempt to detect Unicode encoding by peeking into the stream data to see if it can find the UTF-16 or UTF-32 BOM (Byte Order Mark). If this mark is found, QTextStream will replace the current codec with the UTF codec.

This function can be used together with setCodec(). It is common to set the codec to UTF-8, and then enable UTF-16 detection.

See also autoDetectUnicode() and setCodec().

Sets the codec for this stream to codec. The codec is used for decoding any data that is read from the assigned device, and for encoding any data that is written. By default, QTextCodec::codecForLocale() is used, and automatic unicode detection is enabled.

If QTextStream operates on a string, this function does nothing.

Warning: If you call this function while the text stream is reading from an open sequential socket, the internal buffer may still contain text decoded using the old codec.

See also codec(), setAutoDetectUnicode(), and setLocale().

Sets the codec for this stream to the QTextCodec for the encoding specified by codecName. Common values for codecName include "ISO 8859-1", "UTF-8", and "UTF-16". If the encoding isn't recognized, nothing happens.

Example:

See also QTextCodec::codecForName() and setLocale().

Sets the current device to device. If a device has already been assigned, QTextStream will call flush() before the old device is replaced.

Note: This function resets locale to the default locale ('C') and codec to the default codec, QTextCodec::codecForLocale().

See also device() and setString().

Sets the field alignment to mode. When used together with setFieldWidth(), this function allows you to generate formatted output with text aligned to the left, to the right or center aligned.

See also fieldAlignment() and setFieldWidth().

Sets the current field width to width. If width is 0 (the default), the field width is equal to the length of the generated text.

Note: The field width applies to every element appended to this stream after this function has been called (e.g., it also pads endl). This behavior is different from similar classes in the STL, where the field width only applies to the next element.

See also fieldWidth() and setPadChar().

If generate is true and a UTF codec is used, QTextStream will insert the BOM (Byte Order Mark) before any data has been written to the device. If generate is false, no BOM will be inserted. This function must be called before any data is written. Otherwise, it does nothing.

See also generateByteOrderMark() and bom().

Sets the base of integers to base, both for reading and for generating numbers. base can be either 2 (binary), 8 (octal), 10 (decimal) or 16 (hexadecimal). If base is 0, QTextStream will attempt to detect the base by inspecting the data on the stream. When generating numbers, QTextStream assumes base is 10 unless the base has been set explicitly.

See also integerBase(), QString::number(), and setNumberFlags().

Sets the locale for this stream to locale. The specified locale is used for conversions between numbers and their string representations.

The default locale is C and it is a special case - the thousands group separator is not used for backward compatibility reasons.

See also locale().

Sets the current number flags to flags. flags is a set of flags from the NumberFlag enum, and describes options for formatting generated code (e.g., whether or not to always write the base or sign of a number).

See also numberFlags(), setIntegerBase(), and setRealNumberNotation().

Sets the pad character to ch. The default value is the ASCII space character (' '), or QChar(0x20). This character is used to fill in the space in fields when generating text.

Example:

The string s contains:

See also padChar() and setFieldWidth().

Sets the real number notation to notation (SmartNotation, FixedNotation, ScientificNotation). When reading and generating numbers, QTextStream uses this value to detect the formatting of real numbers.

See also realNumberNotation(), setRealNumberPrecision(), setNumberFlags(), and setIntegerBase().

Sets the precision of real numbers to precision. This value describes the number of fraction digits QTextStream should write when generating real numbers.

The precision cannot be a negative value. The default value is 6.

See also realNumberPrecision() and setRealNumberNotation().

Sets the status of the text stream to the status given.

See also Status, status(), and resetStatus().

Sets the current string to string, using the given openMode. If a device has already been assigned, QTextStream will call flush() before replacing it.

See also string() and setDevice().

Reads and discards whitespace from the stream until either a non-space character is detected, or until atEnd() returns true. This function is useful when reading a stream character by character.

Whitespace characters are all characters for which QChar::isSpace() returns true.

See also operator>>().

Returns the status of the text stream.

See also QTextStream::Status, setStatus(), and resetStatus().

Returns the current string assigned to the QTextStream, or 0 if no string has been assigned.

See also setString() and device().

Writes the character c to the stream, then returns a reference to the QTextStream.

See also setFieldWidth().

Writes the integer number i to the stream, then returns a reference to the QTextStream. By default, the number is stored in decimal form, but you can also set the base by calling setIntegerBase().

See also setFieldWidth() and setNumberFlags().

Writes the real number f to the stream, then returns a reference to the QTextStream. By default, QTextStream stores it using SmartNotation, with up to 6 digits of precision. You can change the textual representation QTextStream will use for real numbers by calling setRealNumberNotation(), setRealNumberPrecision() and setNumberFlags().

See also setFieldWidth(), setRealNumberNotation(), setRealNumberPrecision(), and setNumberFlags().

Writes the string string to the stream, and returns a reference to the QTextStream. The string is first encoded using the assigned codec (the default codec is QTextCodec::codecForLocale()) before it is written to the stream.

See also setFieldWidth() and setCodec().

This is an overloaded function.

Converts c from ASCII to a QChar, then writes it to the stream.

This is an overloaded function.

Writes the unsigned short i to the stream.

This is an overloaded function.

Writes the signed int i to the stream.

This is an overloaded function.

Writes the unsigned int i to the stream.

This is an overloaded function.

Writes the signed long i to the stream.

This is an overloaded function.

Writes the unsigned long i to the stream.

This is an overloaded function.

Writes the qlonglong i to the stream.

This is an overloaded function.

Writes the qulonglong i to the stream.

This is an overloaded function.

Writes the double f to the stream.

This is an overloaded function.

Writes array to the stream. The contents of array are converted with QString::fromAscii().

This is an overloaded function.

Writes the constant string pointed to by string to the stream. string is assumed to be in ISO-8859-1 encoding. This operator is convenient when working with constant string data. Example:

Warning: QTextStream assumes that string points to a string of text, terminated by a '\0' character. If there is no terminating '\0' character, your application may crash.

This is an overloaded function.

Writes ptr to the stream as a hexadecimal number with a base.

Reads a character from the stream and stores it in c. Returns a reference to the QTextStream, so several operators can be nested. Example:

Whitespace is not skipped.

Reads an integer from the stream and stores it in i, then returns a reference to the QTextStream. The number is cast to the correct type before it is stored. If no number was detected on the stream, i is set to 0.

By default, QTextStream will attempt to detect the base of the number using the following rules:

By calling setIntegerBase(), you can specify the integer base explicitly. This will disable the auto-detection, and speed up QTextStream slightly.

Leading whitespace is skipped.

Reads a real number from the stream and stores it in f, then returns a reference to the QTextStream. The number is cast to the correct type. If no real number is detect on the stream, f is set to 0.0.

As a special exception, QTextStream allows the strings "nan" and "inf" to represent NAN and INF floats or doubles.

Leading whitespace is skipped.

Reads a word from the stream and stores it in str, then returns a reference to the stream. Words are separated by whitespace (i.e., all characters for which QChar::isSpace() returns true).

Leading whitespace is skipped.

This is an overloaded function.

Reads a character from the stream and stores it in c. The character from the stream is converted to ISO-5589-1 before it is stored.

See also QChar::toLatin1().

This is an overloaded function.

Stores the integer in the unsigned short i.

This is an overloaded function.

Stores the integer in the signed int i.

This is an overloaded function.

Stores the integer in the unsigned int i.

This is an overloaded function.

Stores the integer in the signed long i.

This is an overloaded function.

Stores the integer in the unsigned long i.

This is an overloaded function.

Stores the integer in the qlonglong i.

This is an overloaded function.

Stores the integer in the qulonglong i.

This is an overloaded function.

Stores the real number in the double f.

This is an overloaded function.

Converts the word to ISO-8859-1, then stores it in array.

See also QString::toLatin1().

This is an overloaded function.

Stores the word in c, terminated by a '\0' character. If no word is available, only the '\0' character is stored.

Warning: Although convenient, this operator is dangerous and must be used with care. QTextStream assumes that c points to a buffer with enough space to hold the word. If the buffer is too small, your application may crash.

If possible, use the QByteArray operator instead.

Use setPadChar() instead.

Use fieldAlignment(), padChar(), fieldWidth(), numberFlags(), integerBase(), realNumberNotation(), and realNumberNotation instead.

Use setFieldAlignment(), setPadChar(), setFieldWidth(), setNumberFlags(), setIntegerBase(), setRealNumberNotation(), and setRealNumberNotation instead.

Use setRealNumberPrecision() instead.

Use readAll() or readLine() instead.

Use setCodec() and setAutoDetectUnicode() instead.

Use setFieldAlignment(), setPadChar(), setFieldWidth(), setNumberFlags(), setIntegerBase(), setRealNumberNotation(), and setRealNumberNotation instead.

Use setFieldAlignment(), setPadChar(), setFieldWidth(), setNumberFlags(), setIntegerBase(), setRealNumberNotation(), and setRealNumberNotation instead.

Use setDevice(0) instead.

Use setFieldAlignment(), setPadChar(), setFieldWidth(), setNumberFlags(), setIntegerBase(), setRealNumberNotation(), and setRealNumberNotation instead.

Use setFieldWidth() instead.