View Source: ftell(3) - Waikato Linux Users Group

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FSEEK
!!!FSEEK
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
----
!!NAME


fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream
!!SYNOPSIS


__#include __


__int fseek( FILE *__''stream''__, long__
''offset''__, int__ ''whence''__);
long ftell( FILE *__''stream''__);
void rewind( FILE *__''stream''__);
int fgetpos( FILE *__''stream''__, fpos_t
*__''pos''__);
int fsetpos( FILE *__''stream''__, fpos_t
*__''pos''__);__
!!DESCRIPTION


The __fseek__ function sets the file position indicator
for the stream pointed to by ''stream''. The new
position, measured in bytes, is obtained by adding
''offset'' bytes to the position specified by
''whence''. If ''whence'' is set to __SEEK_SET__,
__SEEK_CUR__, or __SEEK_END__, the offset is relative
to the start of the file, the current position indicator, or
end-of-file, respectively. A successful call to the
__fseek__ function clears the end-of-file indicator for
the stream and undoes any effects of the ungetc(3)
function on the same stream.


The __ftell__ function obtains the current value of the
file position indicator for the stream pointed to by
''stream''.


The __rewind__ function sets the file position indicator
for the stream pointed to by ''stream'' to the beginning
of the file. It is equivalent to:


(void)fseek(stream, 0L, SEEK_SET)


except that the error indicator for the stream is also
cleared (see clearerr(3)).


The __fgetpos__ and __fsetpos__ functions are
alternate interfaces equivalent to __ftell__ and
__fseek__ (with whence set to __SEEK_SET__), setting
and storing the current value of the file offset into or
from the object referenced by ''pos''. On some non-UNIX
systems an __fpos_t__ object may be a complex object and
these routines may be the only way to portably reposition a
text stream.
!!RETURN VALUE


The __rewind__ function returns no value. Upon successful
completion, __fgetpos__, __fseek__, __fsetpos__
return 0, and __ftell__ returns the current offset.
Otherwise, -1 is returned and the global variable errno is
set to indicate the error.
!!ERRORS


__EBADF__


The ''stream'' specified is not a seekable
stream.


__EINVAL__


The ''whence'' argument to __fseek__ was not
__SEEK_SET__, __SEEK_END__, or
__SEEK_CUR__.


The function __fgetpos__, __fseek__, __fsetpos__,
and __ftell__ may also fail and set ''errno'' for any
of the errors specified for the routines fflush(3),
fstat(2), lseek(2), and
malloc(3).
!!CONFORMING TO


The __fgetpos__, __fsetpos__, __fseek__,
__ftell__, and __rewind__ functions conform to ANSI
X3.159-1989 (``ANSI C'').
!!SEE ALSO


lseek(2)
----

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Last edited on Tuesday, June 4, 2002 12:24:21 am by "perry"

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