Question

I am trying to program using C to write binary data to a .bin file and just iterate through to write from 0000 to FFFF. I figured I would use fopen with a ‘wb’ tag and then be able to write binary data but I’m unsure how to iterate from 0000 to FFFF using C. Thanks for any help.

Here’s my code now:

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

int main()
{
 FILE *f = fopen("binary.bin", "wb");
 unsigned long i;

 //if(f == NULL) { ...error handling... }

 for(i = 0x0000; i <= 0xFFFF; i++){
  // Write something to the file, e.g. the 16-bit (2 byte) value of "i"
  unsigned short someData = i;
  fwrite(&someData, 1, 2, f);
 }

 fclose(f);
 return 0;
 //printf("Hello World\n");
 getchar();
}

This will output 00 00 01 00 02 00 …

Here’s my question now. Isn’t this supposed to read out 00 00 00 01 00 02…Shouldn’t there be an extra ’00’ at the beginning?

Also, I’ve been trying to see how could I copy it and extend it therefore making it 0000 0000 0001 0001 etc?
[Update: I just copied the fwrite line and did it again and it solved this problem]

Answer 1

This is a simple example of writing some binary numbers to a file.

FILE *f = fopen("yourfile", "wb");

if(f == NULL) { ...error handling... }

for(unsigned long i = 0x0000; i <= 0xFFFF; ++i)
{
    // Write something to the file, e.g. the 16-bit (2 byte) value of "i"
    unsigned short someData = i;
    fwrite(&someData, 1, 2, f);
}

fclose(f);

Note that the variable i here must be bigger than 16-bit so that it does not wrap around (see my comments on the other answers). The long type guarantees a size of at least 32 bit.