#include <LiquidCrystal.h>
#include <Keypad.h>
//#include <string>

const int rs = 23, en = 6, d4 = 24, d5 = 5, d6 = 26, d7 = 7;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

char keys[4][4] = {
  {'1', '2', '3', '+'},
  {'4', '5', '6', '-'},
  {'7', '8', '9', '*'},
  {'C', '0', '=', '/'}
};

byte pin_rows[4] = {30, 32, 34, 36};
byte pin_cols[4] = {31, 33, 35, 37};

char text[16];

Keypad keypad = Keypad(makeKeymap(keys), pin_rows, pin_cols, 4, 4);


void setup() {

  pinMode(30, INPUT);
  pinMode(32, INPUT);
  pinMode(34, INPUT);
  pinMode(36, INPUT);
  pinMode(31, INPUT);
  pinMode(33, INPUT);
  pinMode(35, INPUT);
  pinMode(37, INPUT);

  lcd.begin(16, 2);
  lcd.setCursor(0, 1);
  //lcd.print("hello, world!");
  //string text = "Hello";
}

void loop() {
  char value = keypad.getKey();
  if (value) {
    lcd.print(value);
    Serial.println(value);
    if (value == 'C') {
      lcd.clear();
    }
  }
      //text[0] = keypad.getKey();
  //lcd.print(text[0]);
}