Start/Stop program by pushing a button

Projects Programming
1

Hi guys, i've been struggling with a problem in my code. What i want to do is basicaly an on/off method that start/stop the loop. From what i find, i need to put a button that is connected to a input pin and check if the button is pressed or not at the beginning of the loop, but the thing is that i want to turn on/off the program any time while the program is running, but i'm not sure how can i implement that any other way than by simply checking the state of the button over and over again in the loop. Maybe someone can help me with a much simpler way to solve this.

int led[3] = { 3, 4, 5}; // Assign the pins for the leds
int Audio = A0;
int s[3],sm,i,Vth;
void setup() {
	for (i = 0; i < 3; i++)
	pinMode(led[i], OUTPUT);
}
void loop() {
	
	for(i = i; i < 3; i++) {
	digitalWrite(led[i], LOW);}
		
	retry:
		long interval = 5000;
		long currentMillis = 0;
	
		for(i=1;i<=3;i++){
			s[i] = analogRead(Audio);
			currentmillis=millis();
			while(s[i]<Vth){
				s[i] = analogRead(Audio);
				if(millis()-currentmillis>interval)
					goto retry;
				}
		Serial.println(s[i]);
		}

		
	sm=(s[1]+s[2]+s[3])/3;
	sm = sm / 85; //Change the sensitivity by changing Denominator
	if (sm == 0) {
		for(i = 0; i < 3; i++) {
			digitalWrite(led[i], LOW);
			}
		}
	else {
		for (i = 0; i < sm; i++) {
			digitalWrite(led[i], HIGH);
			delay(40);
			}
		for(i = i; i < 3; i++) {
			digitalWrite(led[i], LOW);
			}
		}
	delay(3000);
	}
2

Kind of like a toggle?

bool runCODE;

void loop(){
// read button1

    if(button1 == HIGH && runCODE == false){
      runCODE = true;
    }
    if(button1 == HIGH && runCODE == true){
      runCODE = false;
    }
    if(runCODE == true){dothisFunction();}
}

void dothisFunction(){
  //do stuff here
}
3

The level of button1 never changes in that code. It needs a button1 = digitalRead(button1Pin); somewhere, like at the top of loop().