Inputs in SDL (on key pressed)

Question

I would like to know how can I detect the press of a key or release of a key in a while loop in SDL. Now, I know you can get the events with SDL like OnKeyPressed, OnKeyReleased, OnKeyHit, etc, but I want to know how to build functions like 'KeyPressed' that returns a boolean, instead of being an event. Example:

while not KeyHit( KEY_ESC ) 
{
//Code here
}

Answer 1

I know you have already selected an answer.. but here is some actual code of how I typically do it with one array. :)

first define this somewhere.

bool KEYS[322];  // 322 is the number of SDLK_DOWN events
    
for(int i = 0; i < 322; i++) { // init them all to false
    KEYS[i] = false;
}
    
SDL_EnableKeyRepeat(0,0); // you can configure this how you want, but it makes it nice for when you want to register a key continuously being held down

Then later, create a keyboard() function which will register keyboard input

void keyboard() {
    // message processing loop
    SDL_Event event;
    while (SDL_PollEvent(&event)) {
        // check for messages
        switch (event.type) {
            // exit if the window is closed
        case SDL_QUIT:
            game_state = 0; // set game state to done,(do what you want here)
            break;
            // check for keypresses
        case SDL_KEYDOWN:
            KEYS[event.key.keysym.sym] = true;
            break;
        case SDL_KEYUP:
            KEYS[event.key.keysym.sym] = false;
            break;
        default:
            break;
        }
    } // end of message processing
}

Then when you actually want to use the keyboard input i.e. a handleInput() function, it may look something like this:

void handleInput() {
    if(KEYS[SDLK_LEFT]) { // move left
        if(player->x - player->speed >= 0) {
            player->x -= player->speed;
        }
    }
    if(KEYS[SDLK_RIGHT]) { // move right
        if(player->x + player->speed <= screen->w) {
            player->x += player->speed;
        }
    }
    if(KEYS[SDLK_UP]) { // move up
        if(player->y - player->speed >= 0) {
            player->y -= player->speed;
        }
    }
    if(KEYS[SDLK_DOWN]) { // move down
        if(player->y + player->speed <= screen->h) {
            player->y += player->speed;
        }
    }
    if(KEYS[SDLK_s]) { // shoot 
        if(SDL_GetTicks() - player->lastShot > player->shotDelay) {
            shootbeam(player->beam);
        }
    }
    if(KEYS[SDLK_q]) {
        if(player->beam == PLAYER_BEAM_CHARGE) {
            player->beam = PLAYER_BEAM_NORMAL;
        } else {
            player->beam = PLAYER_BEAM_CHARGE;
        }
    }
    if(KEYS[SDLK_r]) {
        reset();
    }
    
    if(KEYS[SDLK_ESCAPE]) {
        gamestate = 0;
    }
}

And of course you can easily do what you're wanting to do

while(KEYS[SDLK_s]) {
    // do something
    keyboard(); // don't forget to redetect which keys are being pressed!
}

**Updated version on my website: ** For the sake of not posting a lot of source code, you can view a complete SDL Keyboard class in C++ that supports

1. Single Key Input
2. Simultaneous Key Combos (Keys all pressed in any order)
3. Sequential Key Combonations (Keys all pressed in specific order)

http://kennycason.com/posts/2009-09-20-sdl-simple-space-shooter-game-demo-part-i.html (if you have any problems, let me know)