feof

Статья
10/16/2008

Tests for end-of-file on a stream.

int feof( 
   FILE *stream 
);

Параметры

stream
Pointer to FILE structure.

Возвращаемое значение

The feof function returns a nonzero value if a read operation has attempted to read past the end of the file; it returns 0 otherwise. If the stream pointer is NULL, the function invokes the invalid parameter handler, as described in Parameter Validation. If execution is allowed to continue, errno is set to EINVAL and the feof returns 0.

See _doserrno, errno, _sys_errlist, and _sys_nerr for more information on these, and other, error codes.

Заметки

The feof routine (implemented both as a function and as a macro) determines whether the end of stream has been passed. When the end of file is passed, read operations return an end-of-file indicator until the stream is closed or until rewind, fsetpos, fseek, or clearerr is called against it.

For example, if a file contains 10 bytes and you read 10 bytes from the file, feof will return 0 because, even though the file pointer is at the end of the file, you have not attempted to read beyond the end. Only after you try to read an 11th byte will feof return a nonzero value.

Требования

Function	Required header
feof	<stdio.h>

For additional compatibility information, see Compatibility in the Introduction.

Пример

// crt_feof.c
// This program uses feof to indicate when
// it reaches the end of the file CRT_FEOF.TXT. It also
// checks for errors with ferror.
//

#include <stdio.h>
#include <stdlib.h>

int main( void )
{
   int  count, total = 0;
   char buffer[100];
   FILE *stream;

   fopen_s( &stream, "crt_feof.txt", "r" );
   if( stream == NULL )
      exit( 1 );

   // Cycle until end of file reached:
   while( !feof( stream ) )
   {
      // Attempt to read in 100 bytes:
      count = fread( buffer, sizeof( char ), 100, stream );
      if( ferror( stream ) )      {
         perror( "Read error" );
         break;
      }

      // Total up actual bytes read
      total += count;
   }
   printf( "Number of bytes read = %d\n", total );
   fclose( stream );
}