/**
   Arduino Calculator

   Copyright (C) 2020, Uri Shaked.
   Released under the MIT License.
*/


#include <Keypad.h>




/* Keypad setup */
const byte KEYPAD_ROWS = 4;
const byte KEYPAD_COLS = 4;
byte rowPins[KEYPAD_ROWS] = {5, 4, 3, 2};
byte colPins[KEYPAD_COLS] = {A3, A2, A1, A0};
char keys[KEYPAD_ROWS][KEYPAD_COLS] = {
  {'1', '2', '3', '+'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '*'},
  {'.', '0', '=', '/'}
};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, KEYPAD_ROWS, KEYPAD_COLS);


String number= "";
void setup(){
  Serial.begin(9600);
  Serial.println("Press A to reset...");
}

void loop(){
  char key = keypad.getKey();
  if (key){
    
    if(key=='+'){
        Serial.println("Resetting...");
        number="";
    } else if( key >= 48 && key <= 57 && number.length()<3){
        Serial.print(key);
        number+=key;
        if(number.length()==3){
        Serial.println("\nNumber Recorded "+number);
      }
    }
    else{
      Serial.print(key);
      Serial.println("\nInvalid key...\nResetting...");
      number="";
    }
  }
}