How save output histogram as png file?

[Margarett97]

Hi. This is my first code in C I wrote ... it is supposed to create a grayscale image histogram. How do I save the histogram to a png file?
(I'm not sure the code is correct but there are no compile time errors)

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

int main()
{
unsigned char buffer[10];
init disp;
FILE *img;

img = fopen("name.bin", "rb");
disp = fread(buffer, sizeof(buffer), 1, img);

int hist[256] = { 0 };
int col = 1200;
int row = 1500;
int i;
int j;
int J;

for (j = 0; j < row; j++);
{
       for (i = 0; i < col; i++);
       {
              J = (disp + i + j*col);
              hist[J] = hist[J] + 1;
        }
}

[Salem]

> (I'm not sure the code is correct but there are no compile time errors)
Well that would be the first step.

If the code is actually wrong (but you don't know it yet), then even if you're successful with the PNG image, it's still going to look wrong.
That will lead you to the wrong conclusions as to what is broken.

As for drawing, start here -> libpng Home Page
This is quite low level, you'd have to manage all the pixels yourself.