Question

Setup: I have this program in c++:

#include <windows.h>
using namespace std;
int main(){
    HWND window;
    AllocConsole();
    window = FindWindowA("ConsoleWindowClass", NULL);
    ShowWindow(window,0);
while (1){  
if (GetKeyState('A'))
        {
    system("start love.mp3");
    return 0;
        }
    }
return 0;
}

So the program runs as a process and waits until the key A is pressed. And then it plays the love.mp3 file 🙂

However, when the program is waiting it uses up 25% of the CPU usage.

Qustion: Is there a way to reduce this so that the program doesn’t consume so much of the CPU?

Answer 1

Calling Sleep in the loop is sort of effective, but IMO, it’s clearly the wrong way to go.

Instead, I’d do a blocking read, then check if the result was A, and do your thing when it is:

while ((ch = getch()) != EOF)
    if (ch == 'A') {
        system("start love.mp3");
        break;
    }

This won’t miss keystrokes, and it’ll use even less CPU time than a loop that calls Sleep.