#include <stdio.h>
long ftell(FILE *stream);
The ftell() function obtains the current value of the file-position indicator for the stream pointed to by stream. The ftello() function is identical to ftell() except for the return type.
Upon successful completion, the ftell() and ftello() functions return the current value of the file-position indicator for the stream measured in bytes from the beginning of the file. Otherwise, they return -1 and sets errno to indicate the error.
The ftell() and ftello() functions will fail if:
EBADF The file descriptor underlying stream is not an open file descriptor.
ESPIPE The file descriptor underlying stream is associated with a pipe, a FIFO, or a socket.
The ftell() function will fail if:
EOVERFLOW The current file offset cannot be represented correctly in an object of type long.
The ftello() function will fail if:
EOVERFLOW The current file offset cannot be represented correctly in an object of type off_t.
The ftello() function has a transitional interface for 64-bit file offsets. See lf64(5).
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Interface Stability | Standard |
| MT-Level | MT-Safe |
lseek(2), fopen(3C), fseek(3C), attributes(5), , standards(5), lf64(5)