FSEEK

Section: C Library Functions (3)
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BSD mandoc

NAME

fgetpos fseek fsetpos ftell rewind - reposition a stream

SYNOPSIS

Fd #include <stdio.h> Ft int Fn fseek FILE *stream long offset int whence Ft long Fn ftell FILE *stream Ft void Fn rewind FILE *stream Ft int Fn fgetpos FILE *stream fpos_t *pos Ft int Fn fsetpos FILE *stream fpos_t *pos

DESCRIPTION

The Fn fseek function sets the file position indicator for the stream pointed to by Fa stream . The new position, measured in bytes, is obtained by adding Fa offset bytes to the position specified by Fa whence . If Fa 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 Fn 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 Fn ftell function obtains the current value of the file position indicator for the stream pointed to by Fa stream .

The Fn rewind function sets the file position indicator for the stream pointed to by Fa 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 Fn fgetpos and Fn fsetpos functions are alternate interfaces equivalent to Fn ftell and Fn fseek (with whence set to SEEK_SET ), setting and storing the current value of the file offset into or from the object referenced by Fa pos . On some (non- UNIX ) systems an ``Fa fpos_t '' object may be a complex object and these routines may be the only way to portably reposition a text stream.

RETURN VALUES

The Fn rewind function returns no value. Upon successful completion, Fn fgetpos , Fn fseek , Fn fsetpos return 0, and Fn ftell returns the current offset. Otherwise, Fn fseek returns -1 and the others return a nonzero value and the global variable errno is set to indicate the error.

ERRORS

Bq Er EBADF: The Fa stream specified is not a seekable stream.
Bq Er EINVAL: The Fa whence argument to Fn fseek was not SEEK_SET SEEK_END or SEEK_CUR

The function Fn fgetpos , Fn fseek , Fn fsetpos , and Fn ftell may also fail and set errno for any of the errors specified for the routines fflush(3), fstat(2), lseek(2), and malloc(3).

STANDARDS

The Fn fgetpos , Fn fsetpos , Fn fseek , Fn ftell , and Fn rewind functions conform to St -ansiC .

This document was created by man2html, using the manual pages.
Time: 19:42:01 GMT, December 25, 2022