Tests for end of file (EOF).

int _eof( 
   int fd 


  • 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 is not. 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.


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



Required header

Optional header




For more compatibility information, see Compatibility in the Introduction.


// 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" );
      // 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.


Number of bytes read = 29

.NET Framework Equivalent

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

See Also


Error Handling (CRT)

Low-Level I/O




perror, _wperror