Portable Anymap

anymap.c

// Portable Pixmap in C example.
// Compile with: gcc anymap.c -o anymap
// Tutorial: https://nicolashollmann.de/blog/writing-portable-anymap/

#include <stdio.h>

#define WIDTH 300
#define HEIGHT 200

// Uncomment to write binary instead of ASCII
//#define BINARY

int main()
{
    FILE *outfile = fopen("out.ppm", "wb");

    #ifdef BINARY
    fprintf(outfile, "P6");
    #else
    fprintf(outfile, "P3");
    #endif

    fprintf(outfile, "\n%d %d\n255\n", WIDTH, HEIGHT);

    for (int y = 0; y < HEIGHT; y++)
    {
        for (int x = 0; x < WIDTH; x++)
        {
            int r = (x / (float)WIDTH) * 255;
            int g = (x / (float)WIDTH) * 255;
            int b = (y / (float)HEIGHT) * 255;

            #ifdef BINARY
            unsigned char colors[3] = {r, g, b};
            fwrite(colors, 3, 1, outfile);
            #else
            fprintf(outfile, "%3d %3d %3d ", r, g, b);
            #endif
        }
        #ifndef BINARY
        fprintf(outfile, "\n");
        #endif
    }

    fclose(outfile);
    return 0;
}

anymap.cpp

// Portable Pixmap in C++ example.
// Compile with: g++ anymap.cpp -o anymap
// Tutorial: https://nicolashollmann.de/blog/writing-portable-anymap/

#include <iostream>
#include <fstream>

using namespace std;

#define WIDTH 300
#define HEIGHT 200

// Uncomment to write binary instead of ASCII
//#define BINARY

int main()
{
    ofstream outfile;

    outfile.open("out.ppm", ios::out | ios::binary);

    #ifdef BINARY
    outfile << "P6";
    #else
    outfile << "P3";
    #endif

    outfile << "\n" << WIDTH << " " << HEIGHT << "\n255\n";

    for (int y = 0; y < HEIGHT; y++)
    {
        for (int x = 0; x < WIDTH; x++)
        {
            int r = (x / (float)WIDTH) * 255;
            int g = (x / (float)WIDTH) * 255;
            int b = (y / (float)HEIGHT) * 255;

            #ifdef BINARY
            unsigned char colors[3] = {r, g, b};
            outfile.write(colors, 3);
            #else
            outfile << r << " " << g << " " << b << " ";
            #endif
        }
        #ifndef BINARY
        outfile << "\n";
        #endif
    }

    outfile.close();
    return 0;
}