const int pushButton[]={2,3,4,5}; //define push button inputs
const int relayPin[]={8,9,10,11}; //output pins where 4 relays will be connected
String relayNames[]={"CH1","CH2","CH3","CH4"}; //just put name for 4 relays
int pushed[]={0,0,0,0}; //status of each buttons
int relayStatus[]={LOW,LOW,LOW,LOW}; //initial status of relay

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  for(int i=0; i<4; i++){
    pinMode(pushButton[i], INPUT_PULLUP);
    pinMode(relayPin[i], OUTPUT);
    digitalWrite(relayPin[i], LOW); //initial relay status to be PFF
  }
}

void loop() {
  // put your main code here, to run repeatedly:
  for(int i=0; i<4; i++){
    int val = digitalRead(pushButton[i]);

    if(val==HIGH && relayStatus[i]==LOW){
      pushed[i]=1-pushed[i];
      delay(100);
    }
  
    relayStatus[i]=val;

    if(pushed[i]==HIGH){
      Serial.print(relayNames[i]);
      Serial.println("OFF");
      digitalWrite(relayPin[i], LOW);
    }else{
      Serial.print(relayNames[i]);
      Serial.println("ON");
      digitalWrite(relayPin[i], HIGH);
    }
  Serial.println("====");
  }
delay(100);
}