ftell

fsetpos

#include <stdio.h>int fsetpos(FILE *stream, const fpos_t *position);

The fsetpos( ) function moves the file position indicator to the location specified by the object pointed to by position. This value must have
been previously obtained through a call to fgetpos( ). After fsetpos( )
is executed, the end-of-file indicator is reset. Also, any previous call to ungetc( ) is nullified.

If fsetpos( ) fails, it returns nonzero. If it is successful, it returns zero.

Related functions are fgetpos( ), fseek( ), and ftell( ).