FTELL(3) Library Functions Manual FTELL(3)

NAME

ftell ftello — return a file offset in a stream

SYNOPSIS

#include <stdio.h>

long ftell(FILE *stream);
[CX] off_t ftello(FILE *stream);

DESCRIPTION

[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 (“POSIX.1”) defers to the ISO C standard.

The ftell () function shall obtain the current value of the file-position indicator for the stream pointed to by stream.

[CX] The ftello () function shall be equivalent to ftell (), except that the return value is of type off_t.

RETURN VALUE

Upon successful completion, ftell () [CX] and ftello () shall return the current value of the file-position indicator for the stream measured in bytes from the beginning of the file.

Otherwise, ftell () [CX] and ftello () shall return -1, cast to long and off_t respectively, and set errno to indicate the error.

ERRORS

The ftell () [CX] and ftello () functions shall fail if:

[EBADF]: [CX] The file descriptor underlying stream is not an open file descriptor.
[EOVERFLOW]: [CX] For ftell (), the current file offset cannot be represented correctly in an object of type long .
[EOVERFLOW]: [CX] For ftello (), the current file offset cannot be represented correctly in an object of type off_t .
[ESPIPE]: [CX] The file descriptor underlying stream is associated with a pipe or FIFO.