fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream
#include <stdio.h> int fseek(FILE *stream, long offset, int whence); long ftell(FILE *stream); void rewind(FILE *stream); int fgetpos(FILE *stream, fpos_t *pos); int fsetpos(FILE *stream, const fpos_t *pos);
The fseek() function sets the file position indicator for the stream pointed to by
stream. The new position, measured in bytes, is obtained by adding
offset bytes to the position specified by
whence is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the start of the file, the current position indicator, or end-of-file, respectively. A successful call to the fseek() function clears the end-of-file indicator for the stream and undoes any effects of the ungetc(3) function on the same stream.
The ftell() function obtains the current value of the file position indicator for the stream pointed to by
The rewind() function sets the file position indicator for the stream pointed to by
stream to the beginning of the file. It is equivalent to:
(void) fseek(stream, 0L, SEEK_SET)
except that the error indicator for the stream is also cleared (see clearerr(3)).
The fgetpos() and fsetpos() functions are alternate interfaces equivalent to ftell() and fseek() (with
whence set to SEEK_SET), setting and storing the current value of the file offset into or from the object referenced by
pos. On some non-UNIX systems, an
fpos_t object may be a complex object and these routines may be the only way to portably reposition a text stream.
The rewind() function returns no value. Upon successful completion, fgetpos(), fseek(), fsetpos() return 0, and ftell() returns the current offset. Otherwise, -1 is returned and
errno is set to indicate the error.
stream specified is not a seekable stream.
whence argument to fseek() was not SEEK_SET, SEEK_END, or SEEK_CUR. Or: the resulting file offset would be negative.
For an explanation of the terms used in this section, see attributes(7).
|fseek(), ftell(), rewind(),
POSIX.1-2001, POSIX.1-2008, C89, C99.
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