Reads data from a stream.
#include <stdio.h>
size_t fread( void *buffer, size_t size, size_t count, FILE *stream );
| buffer | Storage location for data | |
| size | Item size in bytes | |
| count | Maximum number of items to be read | |
| stream | Pointer to FILE structure |
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–line-feed pairs are replaced with single line-feed 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.
The fread function returns the number of full items actually read, which may be less than count if an error occurs or if the file end is encountered before reaching count.
The feof or ferror function should be used 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.
Standards:ANSI, UNIX
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:DOS32X
/* 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] = '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( "Was not able to open the file\n" );
}
Wrote 25 items
Number of items read = 25
Contents of buffer = zyxwvutsrqponmlkjihgfedcb