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ftell (3)

ftell (3) ( Solaris man: Библиотечные вызовы )

>> ftell (3) ( FreeBSD man: Библиотечные вызовы )

ftell (3) ( Русские man: Библиотечные вызовы )

ftell (3) ( Linux man: Библиотечные вызовы )

ftell (3) ( POSIX man: Библиотечные вызовы )

BSD mandoc

NAME



fgetpos

 
fseek

 
fseeko

 
fsetpos

 
ftell

 
ftello

 
rewind

 - reposition a stream

LIBRARY

Lb libc

SYNOPSIS

#include <stdio.h>
int fseek (FILE *stream long offset int whence);
long ftell (FILE *stream);
void rewind (FILE *stream);
int fgetpos (FILE * restrict stream fpos_t * restrict pos);
int fsetpos (FILE *stream const fpos_t *pos);
#include <sys/types.h>
int fseeko (FILE *stream off_t offset int whence);
off_t ftello (FILE *stream);

DESCRIPTION

The 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 fseek ();
function clears the end-of-file indicator for the stream and undoes any effects of the ungetc(3) and ungetwc(3) functions on the same stream.

The ftell ();
function obtains the current value of the file position indicator for the stream pointed to by Fa stream .

The 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)).

Since rewind ();
does not return a value, an application wishing to detect errors should clear errno then call rewind (,);
and if errno is non-zero, assume an error has occurred.

The fseeko ();
function is identical to fseek (,);
except it takes an Fa off_t argument instead of a Fa long . Likewise, the ftello ();
function is identical to ftell (,);
except it returns an Fa off_t .

The fgetpos ();
and fsetpos ();
functions are alternate interfaces for retrieving and setting the current position in the file, similar to ftell ();
and fseek (,);
except that the current position is stored in an opaque object of type Vt fpos_t pointed to by Fa pos . These functions provide a portable way to seek to offsets larger than those that can be represented by a Vt long int . They may also store additional state information in the Vt fpos_t object to facilitate seeking within files containing multibyte characters with state-dependent encodings. Although Vt fpos_t has traditionally been an integral type, applications cannot assume that it is; in particular, they must not perform arithmetic on objects of this type.

If the stream is a wide character stream (see fwide(3)), the position specified by the combination of Fa offset and Fa whence must contain the first byte of a multibyte sequence.

RETURN VALUES

The rewind ();
function returns no value.

Rv -std fgetpos fseek fseeko fsetpos

Upon successful completion, ftell ();
and ftello ();
return the current offset. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

ERRORS

Bq Er EBADF: The Fa stream argument is not a seekable stream.
Bq Er EINVAL: The Fa whence argument is invalid or the resulting file-position indicator would be set to a negative value.
Bq Er EOVERFLOW: The resulting file offset would be a value which cannot be represented correctly in an object of type Fa off_t for fseeko ();
and ftello ();
or Fa long for fseek ();
and ftell (.);
Bq Er ESPIPE: The file descriptor underlying stream is associated with a pipe or FIFO or file-position indicator value is unspecified (see ungetc(3)).

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