Arduino strings

strings_demo.ino

#define led 13
String input_string = "";
const String Led_off = "switch led off";
const String Led_on = "switch led on";
bool led_running;

void setup() {
  Serial.begin(9600);
}

void loop() {
  while (Serial.available() > 0) {
    char c = Serial.read();
    if (c == '\n') { 
      Serial.print("Input_string is: ");
      Serial.println(input_string);
      switch ( parse(input_string, Led_off, Led_on) ) {
        case 10:
          led_running=false;
          Serial.println("Switching off is done");
          break;
        case 11:
          led_running=true;
          Serial.println("Switching on is done");
          break;
        case 0:
          Serial.println("invalid String");
          break;
      }
      input_string = "";
      digitalWrite(led, led_running);
    } else {
      input_string += c;

    }
  }
}

byte parse(String input_string, const String Led_off, const String Led_on) {
  if (input_string.equals(Led_off) == true) {
    return 10;
  }
  else if (input_string.equals(Led_on) == true) {
    return 11;
  }
  else return 0;
}