fread (Windows CE 5.0)

Artikel
09/14/2012

Developing an Application > Microsoft C Run-time Library for Windows CE > Run-time Library Reference

Reads data from a stream.

size_t fread(    void*buffer,size_tsize,size_tcount,FILE*stream);

Parameters

buffer
Storage location for data.
size
Item size in bytes.
count
Maximum number of items to be read.
stream
Pointer to FILE structure.

Libraries

All versions of the C run-time libraries.

Return Values

fread returns the number of full items actually read, which may be less than count if an error occurs or if the end of the file is encountered before reaching count.

Use the feof or ferror function to distinguish a read error from an end-of-file condition.

If size or count is 0, fread returns 0 and the buffer contents are unchanged.

Remarks

The fread function reads up to count items of size bytes from the input stream and stores them in buffer.

The file pointer associated with stream (if there is one) is increased by the number of bytes actually read.

If the given stream is opened in text mode, carriage return–linefeed pairs are replaced with single linefeed characters. The replacement has no effect on the file pointer or the return value. The file-pointer position is indeterminate if an error occurs.

The value of a partially read item cannot be determined.

Example

/* FREAD.C: This program opens a file named FREAD.OUT and
 * writes 25 characters to the file. It then tries to open
 * FREAD.OUT and read in 25 characters. If the attempt succeeds,
 * the program displays the number of actual items read.
 */

#include <stdio.h>

void main( void )
{
   FILE *stream;
   char list[30];
   int  i, numread, numwritten;

   /* Open file in text mode: */
   if( (stream = fopen( "fread.out", "w+t" )) != NULL )
   {
      for ( i = 0; i < 25; i++ )
         list[i] = (char)('z' - i);
      /* Write 25 characters to stream */
      numwritten = fwrite( list, sizeof( char ), 25, stream );
      printf( "Wrote %d items\n", numwritten );
      fclose( stream );

   }
   else
      printf( "Problem opening the file\n" );

   if( (stream = fopen( "fread.out", "r+t" )) != NULL )
   {
      /* Attempt to read in 25 characters */
      numread = fread( list, sizeof( char ), 25, stream );
      printf( "Number of items read = %d\n", numread );
      printf( "Contents of buffer = %.25s\n", list );
      fclose( stream );
   }
   else
      printf( "File could not be opened\n" );
}

Output

Wrote 25 items
Number of items read = 25
Contents of buffer = zyxwvutsrqponmlkjihgfedcb

Requirements

OS Versions: Windows CE 2.0 and later.
Header: stdlib.h.
Link Library: coredll.dll.

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