62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
|
/*
|
||
|
|
FUNCTION
|
||
|
|
<<fgetpos>>---record position in a stream or file
|
||
|
|
|
||
|
|
INDEX
|
||
|
|
fgetpos
|
||
|
|
|
||
|
|
ANSI_SYNOPSIS
|
||
|
|
#include <stdio.h>
|
||
|
|
int fgetpos(FILE *<[fp]>, fpos_t *<[pos]>);
|
||
|
|
|
||
|
|
TRAD_SYNOPSIS
|
||
|
|
#include <stdio.h>
|
||
|
|
int fgetpos(<[fp]>, <[pos]>)
|
||
|
|
FILE *<[fp]>;
|
||
|
|
fpos_t *<[pos]>;
|
||
|
|
|
||
|
|
DESCRIPTION
|
||
|
|
Objects of type <<FILE>> can have a ``position'' that records how much
|
||
|
|
of the file your program has already read. Many of the <<stdio>> functions
|
||
|
|
depend on this position, and many change it as a side effect.
|
||
|
|
|
||
|
|
You can use <<fgetpos>> to report on the current position for a file
|
||
|
|
identified by <[fp]>; <<fgetpos>> will write a value
|
||
|
|
representing that position at <<*<[pos]>>>. Later, you can
|
||
|
|
use this value with <<fsetpos>> to return the file to this
|
||
|
|
position.
|
||
|
|
|
||
|
|
In the current implementation, <<fgetpos>> simply uses a character
|
||
|
|
count to represent the file position; this is the same number that
|
||
|
|
would be returned by <<ftell>>.
|
||
|
|
|
||
|
|
RETURNS
|
||
|
|
<<fgetpos>> returns <<0>> when successful. If <<fgetpos>> fails, the
|
||
|
|
result is <<1>>. Failure occurs on streams that do not support
|
||
|
|
positioning; the global <<errno>> indicates this condition with the
|
||
|
|
value <<ESPIPE>>.
|
||
|
|
|
||
|
|
PORTABILITY
|
||
|
|
<<fgetpos>> is required by the ANSI C standard, but the meaning of the
|
||
|
|
value it records is not specified beyond requiring that it be
|
||
|
|
acceptable as an argument to <<fsetpos>>. In particular, other
|
||
|
|
conforming C implementations may return a different result from
|
||
|
|
<<ftell>> than what <<fgetpos>> writes at <<*<[pos]>>>.
|
||
|
|
|
||
|
|
No supporting OS subroutines are required.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <stdio.h>
|
||
|
|
|
||
|
|
int
|
||
|
|
_DEFUN (fgetpos, (fp, pos),
|
||
|
|
FILE * fp _AND
|
||
|
|
fpos_t * pos)
|
||
|
|
{
|
||
|
|
*pos = ftell (fp);
|
||
|
|
|
||
|
|
if (*pos != -1)
|
||
|
|
return 0;
|
||
|
|
return 1;
|
||
|
|
}
|