ftell
[return position in a stream or file]
SYNOPSIS
#include
<stdio.h>
long ftell(FILE
*fp);
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.
The result of ftell is the current position for a file identified by fp. If you record this result, you can later use it with fseek to return the file to this position.
In the current implementation, ftell simply uses a character count to represent the file position; this is the same number that would be recorded by fgetpos.
RETURNS
ftell
returns the file position, if possible.
If it cannot do this, it returns -1L.
Failure occurs on streams that do not support positioning; the global,
errno,
indicates this condition with the value,
ESPIPE.
COMPLIANCE
ftell
is required by the ANSI C standard,
but the meaning of its result (when successful) is not specified beyond
requiring that it be acceptable as an a
2a6
rgument to fseek.
In particular, other conforming C implementations may return a different
result from ftell
than what fgetpos
records.
No supporting OS subroutines are required.
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