localVariables.ino

int num = 5;

void setup() {
  Serial.begin(57600);
  delay(1000);

  Serial.print("Num is: ");
  Serial.println(num);
  aFunction(num);
  
  Serial.print("Num is: ");
  Serial.println(num);
  aFunction(num);
}

void loop() {
  
}

void aFunction(int input){
  Serial.print("aFunction says first: ");
  Serial.println(input);
  input = input + 1;
  Serial.print("aFunction says second: ");
  Serial.println(input);
}