Manpage of FSEEK

FSEEK

Section: Linux Programmer's Manual (3)
Updated: 2015-08-08
Index
 

NAME

fgetpos, fseek, fsetpos, ftell, rewind - reposition a stream  

SYNOPSIS

#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); 

DESCRIPTION

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 offsetbytes to the position specified by whence. If whenceis 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 stream.

The rewind() function sets the file position indicator for the stream pointed to by streamto 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 whenceset 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_tobject may be a complex object and these routines may be the only way to portably reposition a text stream.  

RETURN VALUE

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 errnois set to indicate the error.  

ERRORS

EBADF
The streamspecified is not a seekable stream.
EINVAL
The whenceargument to fseek() was not SEEK_SET, SEEK_END, or SEEK_CUR. Or: the resulting file offset would be negative.

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

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
fseek(), ftell(), rewind(),
fgetpos(), fsetpos()
Thread safetyMT-Safe

 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C89, C99.  

SEE ALSO

lseek(2), fseeko(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
SEE ALSO

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