QTextStream(3qt)QTextStream(3qt)NAMEQTextStream - Basic functions for reading and writing text
using a
#include <qtextstream.h>
Inherited by QTextIStream and QTextOStream.
Public Members
enum Encoding { Locale, Latin1, Unicode,
UnicodeNetworkOrder, UnicodeReverse, RawUnicode,
UnicodeUTF8 }
void setEncoding ( Encoding )
void setCodec ( QTextCodec * )
QTextStream ()
QTextStream ( QIODevice * )
QTextStream ( QString *, int mode )
QTextStream ( QString &, int mode ) (obsolete)
QTextStream ( QByteArray, int mode )
QTextStream ( FILE *, int mode )
virtual ~QTextStream ()
QIODevice* device () const
void setDevice ( QIODevice * )
void unsetDevice ()
bool atEnd () const
bool eof () const (obsolete)
QTextStream& operator>> ( QChar & )
QTextStream& operator>> ( char & )
QTextStream& operator>> ( signed short & )
QTextStream& operator>> ( unsigned short & )
QTextStream& operator>> ( signed int & )
QTextStream& operator>> ( unsigned int & )
QTextStream& operator>> ( signed long & )
QTextStream& operator>> ( unsigned long & )
QTextStream& operator>> ( float & )
QTextStream& operator>> ( double & )
QTextStream& operator>> ( char * )
QTextStream& operator>> ( QString & )
QTextStream& operator>> ( QCString & )
QTextStream& operator<< ( QChar )
QTextStream& operator<< ( char )
QTextStream& operator<< ( signed short )
QTextStream& operator<< ( unsigned short )
QTextStream& operator<< ( signed int )
QTextStream& operator<< ( unsigned int )
QTextStream& operator<< ( signed long )
QTextStream& operator<< ( unsigned long )
QTextStream& operator<< ( float )
QTextStream& operator<< ( double )
QTextStream& operator<< ( const char * )
QTextStream& operator<< ( const QString & )
QTextStream& operator<< ( const QCString & )
QTextStream& operator<< ( void * )
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QTextStream& readRawBytes ( char *, uint len )
QTextStream& writeRawBytes ( const char *, uint len )
QString readLine ()
QString read ()
void skipWhiteSpace ()
enum { skipws = 0x0001, left = 0x0002, right = 0x0004,
internal = 0x0008, bin = 0x0010, oct = 0x0020, dec =
0x0040, hex = 0x0080, showbase = 0x0100, showpoint =
0x0200, uppercase = 0x0400, showpos = 0x0800,
scientific= 0x1000, fixed = 0x2000 }
int flags () const
int flags ( int f )
int setf ( int bits )
int setf ( int bits, int mask )
int unsetf ( int bits )
void reset ()
int width () const
int width ( int )
int fill () const
int fill ( int )
int precision () const
int precision ( int )
DESCRIPTION
The QTextStream class provides basic functions for reading
and writing text using a QIODevice.
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()).
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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
MEMBER FUNCTION DOCUMENTATIONQTextStream::QTextStream ()
Constructs a data stream that has no IO device.
QTextStream::QTextStream ( QByteArray a, int mode )
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();
QTextStream::QTextStream ( QIODevice * iod )
Constructs a text stream that uses the IO device iod.
QTextStream::QTextStream ( QString & str, int filemode )
This function is obsolete. It is provided to keep old
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
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code.
This constructor is equivalent to the constructor taking a
QString* parameter.
QTextStream::QTextStream ( QString * str, int filemode )
Constructs a text stream that operates on a Unicode
QString through an internal device.
If you set an encoding or codec with setEncoding() or
setCodec(), this setting is ignored for text streams that
operate on QString.
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 the string
will not be truncated:
QString str = "pi = 3.14";
QTextStream ts( &str, IO_WriteOnly );
ts << "2+2 = " << 2+2; // str == "2+2 = 414"
Note that since QString is Unicode, you should not use
readRawBytes() or writeRawBytes() on such a stream.
QTextStream::QTextStream ( FILE * fh, int mode )
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 );
QTextStream::~QTextStream () [virtual]
Destructs the text stream.
The destructor does not affect the current IO device.
bool QTextStream::atEnd () const
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.
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See also QIODevice::atEnd().
QIODevice * QTextStream::device () const
Returns the IO device currently set.
See also setDevice() and unsetDevice().
bool QTextStream::eof () const
This function is obsolete. It is provided to keep old
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
code.
This function has been renamed to atEnd().
See also QIODevice::atEnd().
Examples: grapher/grapher.cpp
int QTextStream::fill () const
Returns the fill character. The default value is ' '
(space).
int QTextStream::fill ( int f )
Sets the fill character to f. Returns the previous fill
character.
int QTextStream::flags () const
Returns the current stream flags. The default value is 0.
The meaning of the flags are:
skipws - Not currently used - whitespace always skipped
left - Numeric fields are left-aligned
right - Not currently used (by default numerics are right
aligned)
internal - Put any padding spaces between +/- and value
bin - Output and input only in binary
oct - Output and input only in octal
dec - Output and input only in decimal
hex - Output and input only in hexadecimal
showbase - Annotate numeric outputs with 0b, 0, or 0x if
in bin, oct, or hex format
showpoint - Not currently used
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uppercase - Use 0B and 0X rather than 0b and 0x
showpos - Show + for positive numeric values
scientific - Use scientific notation for floating point
values
fixed - Use fixed-point notation for floating point values
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().
int QTextStream::flags ( int f )
Sets the stream flags to f. Returns the previous stream
flags.
See also setf(), unsetf() and flags().
QTextStream & QTextStream::operator<;< ( QChar c )
Writes a char to the stream and returns a reference to the
stream.
The character c is assumed to be Latin1 encoded
independent of the Encoding set for the QTextStream.
QTextStream & QTextStream::operator<;< ( char c )
Writes a char to the stream and returns a reference to the
stream.
QTextStream & QTextStream::operator<;< ( const QCString & s )
Writes s to the stream and returns a reference to the
stream.
The string s is assumed to be Latin1 encoded independent
of the Encoding set for the QTextStream.
QTextStream & QTextStream::operator<;< ( const QString & s )
Writes s to the stream and returns a reference to the
stream.
QTextStream & QTextStream::operator<;< ( const char * s )
Writes a string to the stream and returns a reference to
the stream.
The string s is assumed to be Latin1 encoded independent
of the Encoding set for the QTextStream.
QTextStream & QTextStream::operator<;< ( double f )
Writes a double to the stream and returns a reference to
the stream.
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Writes a float to the stream and returns a reference to
the stream.
QTextStream & QTextStream::operator<;< ( signed int i )
Writes an int to the stream and returns a reference to the
stream.
QTextStream & QTextStream::operator<;< ( signed long i )
Writes a long int to the stream and returns a reference to
the stream.
QTextStream & QTextStream::operator<;< ( signed short i )
Writes a short integer to the stream and returns a
reference to the stream.
QTextStream & QTextStream::operator<;< ( unsigned int i )
Writes an unsigned int to the stream and returns a
reference to the stream.
QTextStream & QTextStream::operator<;< ( unsigned long i )
Writes an unsigned long int to the stream and returns a
reference to the stream.
QTextStream & QTextStream::operator<;< ( unsigned short i )
Writes an unsigned short integer to the stream and returns
a reference to the stream.
QTextStream & QTextStream::operator<;< ( void * ptr )
Writes a pointer to the stream and returns a reference to
the stream.
The ptr is output as an unsigned long hexadecimal integer.
QTextStream & QTextStream::operator>> ( QChar & c )
Reads a char from the stream and returns a reference to
the stream. Note that whitespace is not skipped.
QTextStream & QTextStream::operator>> ( QCString & str )
Reads a word from the stream and returns a reference to
the stream.
QTextStream & QTextStream::operator>> ( QString & str )
Reads a word from the stream and returns a reference to
the stream.
QTextStream & QTextStream::operator>> ( char & c )
Reads a char from the stream and returns a reference to
the stream. Note that whitespace is skipped.
QTextStream & QTextStream::operator>> ( char * s )
Reads a word from the stream and returns a reference to
the stream.
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Reads a double from the stream and returns a reference to
the stream. See flags() for an explanation of expected
input format.
QTextStream & QTextStream::operator>> ( float & f )
Reads a float from the stream and returns a reference to
the stream. See flags() for an explanation of expected
input format.
QTextStream & QTextStream::operator>> ( signed int & i )
Reads a signed int from the stream and returns a reference
to the stream. See flags() for an explanation of expected
input format.
QTextStream & QTextStream::operator>> ( signed long & i )
Reads a signed long int from the stream and returns a
reference to the stream. See flags() for an explanation of
expected input format.
QTextStream & QTextStream::operator>> ( signed short & i )
Reads a signed short integer from the stream and returns a
reference to the stream. See flags() for an explanation of
expected input format.
QTextStream & QTextStream::operator>> ( unsigned int & i )
Reads an unsigned int from the stream and returns a
reference to the stream. See flags() for an explanation of
expected input format.
QTextStream & QTextStream::operator>> ( unsigned long & i )
Reads an unsigned long int from the stream and returns a
reference to the stream. See flags() for an explanation of
expected input format.
QTextStream & QTextStream::operator>> ( unsigned short & i )
Reads an unsigned short integer from the stream and
returns a reference to the stream. See flags() for an
explanation of expected input format.
int QTextStream::precision () const
Returns the precision. The default value is 6.
int QTextStream::precision ( int p )
Sets the precision to p. Returns the previous precision
setting.
QString QTextStream::read ()
Reads the entire stream and returns a string containing
the text.
See also QIODevice::readLine().
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QTextStream(3qt)QTextStream(3qt)QString QTextStream::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.
On EOF you will get a QString that is null. On reading an
empty line the returned QString is empty but not null.
See also QIODevice::readLine().
QTextStream & QTextStream::readRawBytes ( char * s, uint len )
Reads len bytes from the stream into e s and returns a
reference to the stream.
The buffer s must be preallocated.
Note that 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().
void QTextStream::reset ()
Resets the text stream.
All flags are set to 0.
The field width is set to 0.
The fill character is set to ' ' (space).
The precision is set to 6.
See also setf(), width(), fill() and precision().
void QTextStream::setCodec ( QTextCodec * codec )
Sets the codec for this stream to codec. Will not try to
autodetect Unicode.
Note that this function should be called before any data
is read to/written from the stream.
See also setEncoding().
void QTextStream::setDevice ( QIODevice * iod )
Sets the IO device to iod.
See also device() and unsetDevice().
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QTextStream(3qt)QTextStream(3qt)void QTextStream::setEncoding ( Encoding e )
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).
UnicodeUTF8 Using Unicode(utf8) for input and output. If
you use it for input it will autodetect utf16 and use it
instead of utf8.
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 that this function should be called before any data
is read to/written from the stream.
See also setCodec().
int QTextStream::setf ( int bits )
Sets the stream flag bits bits. Returns the previous
stream flags.
Equivalent to flags( flags() | bits ).
See also setf() and unsetf().
int QTextStream::setf ( int bits, int mask )
Sets the stream flag bits bits with a bit mask mask.
Returns the previous stream flags.
Equivalent to flags( (flags() & ~mask) | (bits & mask) ).
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See also setf() and unsetf().
void QTextStream::skipWhiteSpace ()
Positions the read pointer at the first non-whitespace
character.
void QTextStream::unsetDevice ()
Unsets the IO device. Equivalent to setDevice( 0 ).
See also device() and setDevice().
int QTextStream::unsetf ( int bits )
Clears the stream flag bits bits. Returns the previous
stream flags.
Equivalent to flags( flags() & ~mask ).
See also setf().
int QTextStream::width () const
Returns the field width. The default value is 0.
int QTextStream::width ( int w )
Sets the field width to w. Returns the previous field
width.
QTextStream & QTextStream::writeRawBytes ( const char * s, uint
len )
Writes the len bytes from s to the stream and returns a
reference to the stream.
Note that no encoding is done by this function.
See also QIODevice::writeBlock().
SEE ALSO
http://doc.trolltech.com/qtextstream.html
http://www.trolltech.com/faq/tech.html
COPYRIGHT
Copyright 1992-2001 Trolltech AS,
http://www.trolltech.com. See the license file included
in the distribution for a complete license statement.
AUTHOR
Generated automatically from the source code.
BUGS
If you find a bug in Qt, please report it as described in
http://doc.trolltech.com/bughowto.html. Good bug reports
make our job much simpler. Thank you.
In case of content or formattting problems with this
manual page, please report them to qt-bugs@trolltech.com.
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Please include the name of the manual page
(qtextstream.3qt) and the Qt version (2.3.1).
Trolltech AS 13 June 2001 12
