Q49872: Fread() Can Read More Than 64K at a Time

Article: Q49872
Product(s): See article
Version(s): 5.10   | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | S_QuickC | mspl13_c
Last Modified: 30-NOV-1989

It is possible to read more than 64K at a time with the fread()
function by specifying an item size greater than 1 and a count from 1
to 64K. The resulting number of bytes read will be the product of size
and count.

The follow code demonstrates how to read a file 200K in length:

/* Must be compiled in huge memory model */
#include <stdio.h>

char huge buffer[205000];

void main(void)
{
     FILE *fp;

     fp=fopen("testfile.dat","r");

     fread(buffer,4,51200,fp);     /* 51200*4=204,800 */

    /* The value returned from the line above will be the number of
       items read. This number is limited to 64K because it is of
       type size_t. But remember, the total number of bytes read is
       equal to the number of items times the size of each item, which
       is 4 bytes in this case. Therefore, the total bytes read
       is 4 times 51200 or 204,800 bytes. */
}

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