ftell(), ftello(), ftello64()
Return the current position of a stream
Synopsis:
#include <stdio.h>
long int ftell( FILE* fp );
off_t ftello( FILE* fp );
off64_t ftello64( FILE* fp );
Arguments:
- fp
- The stream that you want to get the current position of.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The ftell(), ftello(), and ftello64() functions return the current position of the stream specified by fp. This position defines the character that will be read or written by the next I/O operation on the file. The difference between these functions is the data type of the returned position. The ftello64() function is a large-file support version of ftello().
Classificationin What's in a Function Description?
You can use the value returned by an ftell() function in a subsequent call to fseek(), fseeko(), or fseeko64() to restore the file position to a previous value.
Returns:
The current position
of the file, or -1L if an error occurred
(errno is set).
Examples:
#include <stdio.h>
#include <stdlib.h>
long filesize( FILE *fp )
{
long int save_pos;
long size_of_file;
/* Save the current position. */
save_pos = ftell( fp );
/* Jump to the end of the file. */
fseek( fp, 0L, SEEK_END );
/* Get the end position. */
size_of_file = ftell( fp );
/* Jump back to the original position. */
fseek( fp, save_pos, SEEK_SET );
return( size_of_file );
}
int main( void )
{
FILE *fp;
fp = fopen( "file", "r" );
if( fp != NULL ) {
printf( "File size=%ld\n", filesize( fp ) );
fclose( fp );
return EXIT_SUCCESS;
}
return EXIT_FAILURE;
}
Classification:
ftell() is ANSI, POSIX 1003.1; ftello() is POSIX 1003.1; ftello64() is Large-file support
| Safety: | |
|---|---|
| Cancellation point | Yes |
| Signal handler | No |
| Thread | Yes |