1.12.6 <stdio.h>: File Positioning

int fseek(FILE *stream, long offset, int origin)

fseek sets the file position for stream; a subsequent read or write will access data beginning at the new position.  For a binary file, the position is set to offset characters from origin, which may be SEEK_SET (beginning), SEEK_CUR (current position), or SEEK_END (end of file).  For a text stream, offset must be zero, or a value returned by ftell (in which case origin must be SEEK_SET).

long ftell(FILE *stream)

ftell returns the current file position for stream, or -1L on error.

void rewind(FILE *stream)

rewind(fp) is equivalent to fseek(fp, 0L, SEEK_SET); clearerr(fp).

int fgetpos(FILE *stream, fpos_t *ptr)

fgetpos records the current position in stream in *ptr, for subsequent use by fsetpos.  The type fpos_t is suitable for recording such values.  fgetpos returns non-zero on error.

int fsetpos(FILE *stream, const fpos_t *ptr)

fsetpos positions stream at the position recorded by fgetpos in *ptr.  fsetpos returns non-zero on error.