`_eof`

Article
12/02/2022

Tests for end of file (EOF).

Syntax

int _eof(
   int fd
);

Parameters

fd
File descriptor referring to the open file.

Return value

_eof returns 1 if the current position is end of file, or 0 if it isn't. A return value of -1 indicates an error; in this case, the invalid parameter handler is invoked, as described in Parameter validation. If execution is allowed to continue, errno is set to EBADF, which indicates an invalid file descriptor.

Remarks

The _eof function determines whether the end of the file associated with fd has been reached.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function	Required header	Optional header
`_eof`	<io.h>	<errno.h>

For more compatibility information, see Compatibility.

Example

// crt_eof.c
// This program reads data from a file
// ten bytes at a time until the end of the
// file is reached or an error is encountered.
//
#include <io.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <share.h>

int main( void )
{
   int  fh, count, total = 0;
   char buf[10];
   if( _sopen_s( &fh, "crt_eof.txt", _O_RDONLY, _SH_DENYNO, 0 ) )
   {
        perror( "Open failed");
        exit( 1 );
   }
   // Cycle until end of file reached:
   while( !_eof( fh ) )
   {
      // Attempt to read in 10 bytes:
      if( (count = _read( fh, buf, 10 )) == -1 )
      {
         perror( "Read error" );
         break;
      }
      // Total actual bytes read
      total += count;
   }
   printf( "Number of bytes read = %d\n", total );
   _close( fh );
}

Input: crt_eof.txt

This file contains some text.

Output

Number of bytes read = 29

Share via