wth.cpp

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

struct Color
{
    unsigned char r, g, b;
};

int main()
{
    const unsigned num_pixels = 64 * 64;
    Color colors[num_pixels];
    memset(colors, 0, num_pixels * sizeof(Color));

    for (unsigned i = 0; i < num_pixels; ++i)
    {
        colors[i].r = rand()%255;
    }

    FILE* write_handle = fopen("red_noise.data", "w");
    fwrite(colors, 1, num_pixels * sizeof(Color), write_handle);
    fclose(write_handle);

    FILE* read_handle = fopen("red_noise.data", "r");
    fseek(read_handle, 0, SEEK_END);
    size_t filesize = ftell(read_handle);
    fseek(read_handle, 0, SEEK_SET);
    Color* read_colors = (Color*)malloc(filesize);
    fread(read_colors, 1, filesize, read_handle);
    fclose(read_handle);

    for (unsigned i = 0; i < num_pixels; ++i)
    {
        if(read_colors[i].r != colors[i].r
            || read_colors[i].g != colors[i].g
            || read_colors[i].b != colors[i].b)
        {
            printf("At pixel %u: Expected [%u %u %u] Got [%u %u %u]", i,
                colors[i].r, colors[i].g, colors[i].b,
                read_colors[i].r, read_colors[i].g, read_colors[i].b);
            return 1;
        }
    }

    free(read_colors);
    return 0;
}