Why is my key triggered when I only move my mouse

Question

I wrote a function to move the camera for my simple 3D game. I kept running into the problem where the mouse movement function for some reason triggers my Escape key, which I temporarily use to close the program, even though I didn't press it. When I add a few more else if(event.key.keysym.sym == ...) with other keys, it also trigger them.

Here is the code for polling event in the main game loop:

void game::userInput()
{
    while(SDL_PollEvent(&event) != 0)
    {
        if(event.type == SDL_QUIT)
        {
            cout << "quit";
            running = false;
        }
        else if(event.key.keysym.sym == SDLK_ESCAPE)
        {
            cout << event.key.keysym.sym << endl;
            running = false;
        }
        else
        {
            square->input_mouse(event);
        }
    }
}

Here is the code for taking mouse input

void input_mouse(SDL_Event event)
    {
        float mouse_sensitivity = 0.001;
        if(event.type == SDL_MOUSEMOTION)
        {
            int mxo = event.motion.xrel;
            if(mxo < 0)
            {
                cout << "Looking left" << endl;
            }
            else if(mxo > 0)
            {
                cout << "Looking right" << endl;
            }
        }
    }

Answer 1

You have to check that event.type is SDL_KEYDOWN or SDL_KEYUP before accessing event.key.*, similar to how you're checking for SDL_MOUSEMOTION in input_mouse().