Need some tips for code

Using Arduino Programming Questions
4

Hi end up with this

#include <RCSwitch.h>

RCSwitch mySwitch = RCSwitch();

int Relay[]={0,3,4,5,6,7,8,9,13};
int value;
int protocole;
String sensorID;
String state;
String activate;

void setup() {
  Serial.begin(9600);
  mySwitch.enableReceive(0);  // Receiver on inerrupt 0 => that is pin #2
  for(byte i=1; i<9; i++)
{
   pinMode(Relay[i], OUTPUT);
}
}

void loop() {
  if (mySwitch.available()) {
    
    value = mySwitch.getReceivedValue();
    protocole =mySwitch.getReceivedProtocol();
    String code = String(value);
    activate = code.substring(0,2);
    if ((activate == "99") && (protocole == 1)){
    int length = code.length();
    sensorID = code.substring(2,length-1);
    state    = code.substring(length-1);
    if (state == "1"){ 
       int test = sensorID.toInt();
       digitalWrite(Relay[test], HIGH);
    }
    else if (state == "0"){
      int test = sensorID.toInt();
      digitalWrite(Relay[test], LOW);
    }
    delay(500);
    mySwitch.resetAvailable();
    
    }
  }
}