SDL inputs only working sometimes - c++

Question

I am experimenting with keyboard input in SDL and I have encountered a strange problem. Whenever I get input it only outputs the appropriate response sometimes (Clicking X only sometimes closes the program, pressing 1 only sometimes outputs "you pressed 1". Here is my main code:
#include <iostream>
#include <SDL.h>
#include "Screen.h"
#include "Input.h"
using namespace std;
int main(int argc, char *argv[]) {
Screen screen;
Input input;
if (screen.init() == false) {
cout << "Failure initializing SDL" << endl;
}
while (true) {
if (input.check_event() == "1") {
cout << "You pressed 1" << endl;
} else if (input.check_event() == "quit") {
break;
}
}
SDL_Quit();
return 0;
and here is my Input class:
#include <iostream>
#include <SDL.h>
#include "Input.h"
using namespace std;
string Input::check_event() {
while (SDL_PollEvent(&event)) {
if (event.type == SDL_QUIT) {
return "quit";
}
else if(event.type == SDL_KEYDOWN){
switch(event.key.keysym.sym){
case SDLK_1:
return "1";
}
}
}
return "null";
}
Any help would be appreciated!

Answer 1

From the documentation of SDL_PollEvent():
If event is not NULL, the next event is removed from the queue and
stored in the SDL_Event structure pointed to by event.
Analyzing your code:
if (input.check_event() == "1") {
This removes the event, whatever it is, from the queue.
} else if (input.check_event() == "quit") {
Say the return value of the 1st call to check_event() was "quit", then this call won't return "quit" again, because this information is now lost.
To fix that, call check_event() only once per loop iteration and store the result in a temporary variable. Then use only that variable in the conditions:
while (true) {
string event = input.check_event();
if (event == "1") {
cout << "You pressed 1" << endl;
} else if (event == "quit") {
break;
}
}