A tribute to XKCD: the light comes on when I compile!

gistfile1.cpp

/*
 * Based  on this picture
 * http://imgur.com/ZZxFy
 */

#include <cstdio>
#include <stdio.h>
#include <windows.h>
#include <tlhelp32.h>



int main(int, char **)
{
    HANDLE device;

    if ((device = CreateFile("LPT1", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL)) == INVALID_HANDLE_VALUE) {
        printf("Port couldn't be opend: %li\n", GetLastError());
        return -1;
    }

    PROCESSENTRY32 entry;
    entry.dwSize = sizeof(PROCESSENTRY32);
    const char* processName = "make";

    for (;;) {
        unsigned char data = 0x00;
        HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, NULL);

        if (Process32First(snapshot, &entry)) {
            while (Process32Next(snapshot, &entry)) {
                if (stricmp(entry.szExeFile, processName) == 0) {
                    data = ~data;
                    break;
                }
            }
        }

        WriteFile(device, &data, sizeof(data), NULL, NULL);

        CloseHandle(snapshot);
        Sleep(500);
    }

    CloseHandle(device);

    return 0;
}