fwrite creates corrupt files - c

Question

Im having trouble with fwrite corrupting files.
The idea behind this program is to just create a RAW image file that exists out of pixels that I inserted into an array called Colors[]. Basically is should be making straight lines of the different colors im placing into the arrays. Now ive tried a whole lot of methods to write it into a file but if it hasnt been written out in bit mode it just doesnt work on my RAW image display program that I have created although other RAW images do work on it though.
Would there be any easier ways of doing exactly this that I want to do ?
There a version of this program where i use an array of chars to fill the buffer but its a whole lot more code. eX //unsigned char Col[] = {'f','f','f','f','f','f'};
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char *readFile(char *fileName);
int main()
{
unsigned int i;
//Pixels in 24Bit mode
unsigned int Colors[] = {0x00ff00,0x00ffff,0xffff00,0xffff00};
FILE *fpw;
fpw=fopen("MF.bin", "wb");
/*A Buffer array for the pixels to be stored in before fwrite will be used to
dump the entire array to a file.
640pixels by 480pixels * 3(each pixel has 3 ints)
*/
unsigned int Buff[640*480*3];
int y,z,CP=0;
unsigned long x;
for (y=0;y<=(480);y++)
{
if (x>=640)
{
CP = 0;
}
for(x=0;x<=640;x++)//3840);x++)
{
if ((x>=320))
{
CP = 1;
}
if ((x>=159) && (x<319))
{
CP = 1;
}
else if ((x>=319) && (x<439))
{
CP = 2;
}
else if ((x>=439) && (x<640))
{
CP = 0;
}
else if (x>=640)
{
CP =0;
}
Buff[480*y + x] = Colors[CP];
printf("%u--%u,%u\n",(480*y + x),Buff[480 + x], Colors[CP]);
}
unsigned int xx = fwrite(Buff, 1, sizeof(Buff)/sizeof(Buff[0]), fpw);
printf("--&z--",xx);
}
fclose(fpw);
}

Answer 1

There are a few mistakes...
Buff[480*y + x] = Colors[CP];
should be
Buff[640*y + x] = Colors[CP];
and the y loop should be < 480 not <=, same for x.
You are using unsigned ints so you don't need to multiply by 3 in your new. Using fwrite to directly write out 24 bit data won't work like that, as you have an array of 32 bit data, and your calculation for how many bytes to write is incorrect (you need to multiply not divide, but as stated above that would also be wrong because you have 32 bit data instead of 24).
There's no 24 bit data type, so you should use an array of unsigned char not unsigned long and do each colour component individually.