fsetpos
Sets the stream-position indicator.
intfsetpos(FILE*stream,constfpos_t*pos);
| Function | Required Header | Compatibility |
| fsetpos | <stdio.h> | ANSI, Win 95, Win NT |
For additional compatibility information, see Compatibility in the Introduction.
Libraries
| LIBC.LIB | Single thread static library, retail version |
| LIBCMT.LIB | Multithread static library, retail version |
| MSVCRT.LIB | Import library for MSVCRT.DLL, retail version |
Return Value
If successful, fsetpos returns 0. On failure, the function returns a nonzero value and sets errno to one of the following manifest constants (defined in ERRNO.H): EBADF, which means the file is not accessible or the object that stream points to is not a valid file handle; or EINVAL, which means an invalid stream value was passed.
Parameters
stream
Pointer to FILE structure
pos
Position-indicator storage
Remarks
The fsetpos function sets the file-position indicator for stream to the value of pos, which is obtained in a prior call to fgetpos against stream. The function clears the end-of-file indicator and undoes any effects of ungetc on stream. After calling fsetpos, the next operation on stream may be either input or output.
Example
/* FGETPOS.C: This program opens a file and reads
* bytes at several different locations.
*/
#include <stdio.h>
void main( void )
{
FILE *stream;
fpos_t pos;
char buffer[20];
if( (stream = fopen( "fgetpos.c", "rb" )) == NULL )
printf( "Trouble opening file\n" );
else
{
/* Read some data and then check the position. */
fread( buffer, sizeof( char ), 10, stream );
if( fgetpos( stream, &pos ) != 0 )
perror( "fgetpos error" );
else
{
fread( buffer, sizeof( char ), 10, stream );
printf( "10 bytes at byte %ld: %.10s\n", pos, buffer );
}
/* Set a new position and read more data */
pos = 140;
if( fsetpos( stream, &pos ) != 0 )
perror( "fsetpos error" );
fread( buffer, sizeof( char ), 10, stream );
printf( "10 bytes at byte %ld: %.10s\n", pos, buffer );
fclose( stream );
}
}
Output
10 bytes at byte 10: .C: This p
10 bytes at byte 140:
{
FIL
See Also fgetpos