The QTextStream class provides basic functions for reading and writing text using a QIODevice. More...
#include <qtextstream.h>
Inherited by QTextIStream and QTextOStream.
The text stream class has a functional interface that is very similar to that of the standard C++ iostream class. The difference between iostream and QTextStream is that our stream operates on a QIODevice, which is easily subclassed, while iostream operates on FILE * pointers, which can not be subclassed.
Qt provides several global functions similar to the ones in iostream:
bin
sets the QTextStream to read/write binary numbers
oct
sets the QTextStream to read/write octal numbers
dec
sets the QTextStream to read/write decimal numbers
hex
sets the QTextStream to read/write hexadecimal numbers
endl
forces a line break
flush
forces the QIODevice to flush any buffered data
ws
eats any available white space (on input)
reset
resets the QTextStream to its default mode (see reset()).
Warning: By default, QTextStream will automatically detect whether integers in the stream are in decimal, octal, hexadecimal or binary format when reading from the stream. In particular, a leading '0' signifies octal, ie. the sequence "0100" will be interpreted as 64.
The QTextStream class reads and writes text and it is not appropriate for dealing with binary data (but QDataStream is).
By default output of Unicode text (ie. QString) is done using the local 8-bit encoding. This can be changed using the setEncoding() method. For input, the QTextStream will auto-detect standard Unicode "byte order marked" text files, but otherwise the local 8-bit encoding is used.
See also: QDataStream.
Examples: grapher/grapher.cpp
Constructs a data stream that has no IO device.
Constructs a text stream that uses the IO device d.
This function is obsolete. It is provided to keep old programs working. We strongly advise against using it in new code.
This constructor is equivalent to the constructor taking a QString* parameter.
Constructs a text stream that operates on a Unicode QString through an internal device.
Example:
QString str; QTextStream ts( &str, IO_WriteOnly ); ts << "pi = " << 3.14; // str == "pi = 3.14..."
Writing data to the text stream will modify the contents of the string. The string will be expanded when data is written beyond the end of the string.
Note that since QString is Unicode, you should not use readRawBytes() or writeRawBytes() on such a stream.
Constructs a text stream that operates on an existing file handle fh through an internal QFile device.
Example:
QTextStream cout( stdout, IO_WriteOnly ); QTextStream cin ( stdin, IO_ReadOnly ); QTextStream cerr( stderr, IO_WriteOnly );
Constructs a text stream that operates on a byte array through an internal QBuffer device.
Example:
QByteArray array; QTextStream ts( array, IO_WriteOnly ); ts << "pi = " << 3.14 << '\0'; // array == "pi = 3.14"
Writing data to the text stream will modify the contents of the array. The array will be expanded when data is written beyond the end of the string.
Same example, using a QBuffer:
QByteArray array; QBuffer buf( array ); buf.open( IO_WriteOnly ); QTextStream ts( &buf ); ts << "pi = " << 3.14 << '\0'; // array == "pi = 3.14" buf.close();
[virtual]
Destroys the text stream.
The destructor does not affect the current IO device.
Returns TRUE if the IO device has reached the end position (end of stream or file) or if there is no IO device set.
Returns FALSE if the current position of the read/write head of the IO device is somewhere before the end position.
See also: QIODevice::atEnd().
Returns the IO device currently set.
See also: setDevice() and unsetDevice().
This function is obsolete. It is provided to keep old programs working. We strongly advise against using it in new code.
This function has been renamed to atEnd().
See also: QIODevice::atEnd().
Examples: grapher/grapher.cpp
Returns the fill character. The default value is ' ' (space).
Sets the fill character to f. Returns the previous fill character.
Returns the current stream flags. The default value is 0.
The meaning of the flags are:
Note that unless bin, oct, dec, or hex is set, the input base is octal if the value starts with 0, hexadecimal if it starts with 0x, binary if the value starts with 0b, and decimal otherwise.
See also: setf() and unsetf().
Sets the stream flags to f. Returns the previous stream flags.
See also: setf(), unsetf() and flags().
Writes a char
to the stream and returns a reference to the stream.
Writes a string to the stream and returns a reference to the stream.
Writes a string to the stream and returns a reference to the stream.
Writes a double
to the stream and returns a reference to the stream.
Writes a float
to the stream and returns a reference to the stream.
Writes an int
to the stream and returns a reference to
the stream.
Writes a long int
to the stream and returns a reference to
the stream.
Writes a short
integer to the stream and returns a reference to
the stream.
Writes an unsigned int
to the stream and returns a reference to
the stream.
Writes an unsigned long int
to the stream and returns a reference to
the stream.
Writes an unsigned short
integer to the stream and returns a reference
to the stream.
Writes a pointer to the stream and returns a reference to the stream.
The ptr is output as an unsigned long hexadecimal integer.
Reads a char
from the stream and returns a reference to the stream.
Note that whitespace is \em not skipped.
Reads a word from the stream and returns a reference to the stream.
Reads a word from the stream and returns a reference to the stream.
Reads a char
from the stream and returns a reference to the stream.
Note that whitespace is skipped.
Reads a word from the stream and returns a reference to the stream.
Reads a double
from the stream and returns a reference to the stream.
See flags() for an explanation of expected input format.
Reads a float
from the stream and returns a reference to the stream.
See flags() for an explanation of expected input format.
Reads a signed int
from the stream and returns a reference to the
stream. See flags() for an explanation of expected input format.
Reads a signed long
int from the stream and returns a reference to the
stream. See flags() for an explanation of expected input format.
Reads a signed short
integer from the stream and returns a reference to
the stream. See flags() for an explanation of expected input format.
Reads an unsigned int
from the stream and returns a reference to the
stream. See flags() for an explanation of expected input format.
Reads an unsigned long
int from the stream and returns a reference to the
stream. See flags() for an explanation of expected input format.
Reads an unsigned short
integer from the stream and returns a reference to
the stream. See flags() for an explanation of expected input format.
Returns the precision. The default value is 6.
Sets the precision to p. Returns the previous precision setting.
Reads the entire stream and returns a string containing the text.
See also: QIODevice::readLine().
Reads a line from the stream and returns a string containing the text.
The returned string does not contain any trailing newline or carriage return. Note that this is different from QIODevice::readLine(), which does not strip the newline at the end of the line.
See also: QIODevice::readLine().
Reads len bytes from the stream into e s and returns a reference to the stream.
The buffer s must be preallocated.
\note No Encoding is done by this function.
Warning: The behaviour of this function is undefined unless the stream's encoding is set to Unicode or Latin1.
See also: QIODevice::readBlock().
Resets the text stream.
See also: setf(), width(), fill() and precision().
Sets the codec for this stream to codec. Will not try to autodetect Unicode.
\note This function should be called before any data is read to/written from the stream.
See also: setEncoding.
Sets the IO device to d.
See also: device() and unsetDevice().
Sets the encoding of this stream to e, where e is one of:
Locale
Using local file format (Latin1 if locale is not
set), but autodetecting Unicode(utf16) on input.
Unicode
Using Unicode(utf16) for input and output. Output
will be written in the order most efficient for the current platform
(i.e. the order used internally in QString).
Latin1
ISO-8859-1. Will not autodetect utf16.
UnicodeNetworkOrder
Using network order Unicode(utf16) for
input and output. Useful when reading Unicode data that does not
start with the byte order marker.
UnicodeReverse
Using reverse network order Unicode(utf16)
for input and output. Useful when reading Unicode data that does not
start with the byte order marker, or writing data that should be
read by buggy Windows applications.
RawUnicode
Like Unicode, but does not write the byte order
marker, nor does it autodetect the byte order. Only useful when
writing to non-persistent storage used by a single process.
Locale
and all Unicode encodings, except RawUnicode,
will look
at the first two bytes in a input stream to determine the byte
order. The initial byte order marker will be stripped off before data is read.
\note This function should be called before any data is read to/written from the stream.
See also: setCodec.
Sets the stream flag bits bits. Returns the previous stream flags.
Equivalent to flags( flags() | bits )
.
See also: setf() and unsetf().
Sets the stream flag bits bits with a bit mask mask. Returns the previous stream flags.
Equivalent to flags( (flags() & ~mask) | (bits & mask) )
.
See also: setf() and unsetf().
Equivalent to *this << ws.
Unsets the IO device. Equivalent to setDevice( 0 ).
See also: device() and setDevice().
Clears the stream flag bits bits. Returns the previous stream flags.
Equivalent to flags( flags() & ~mask )
.
See also: setf().
Returns the field width. The default value is 0.
Sets the field width to w. Returns the previous field width.
Writes the len bytes from s to the stream and returns a reference to the stream.
\note No Encoding is done by this function.
See also: QIODevice::writeBlock().
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