/*

https://forum.arduino.cc/t/lcd-text-being-corrupted-by-something/1261627

*/



#include <Keypad.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);
const byte ROWS = 4;  //four rows
const byte COLS = 4;  //three columns
char keys[ROWS][COLS] = {
  { '1', '2', '3', 'A' },
  { '4', '5', '6', 'B' },
  { '7', '8', '9', 'C' },
  { '*', '0', '#', 'D' }
};
char str[17] = "                ";
byte rowPins[ROWS] = { 5, 4, 3, 2 };  //connect to the row pinouts of the keypad
byte colPins[COLS] = { 9, 8, 7, 6 };  //connect to the column pinouts of the keypad
int d = 0;
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

void setup() {
  Serial.begin(115200);
  lcd.init();  // initialize the lcd
  lcd.init();
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("PLAY SONG NUMBER....");
  lcd.setCursor(0, 1);
  lcd.print("");
  lcd.setCursor(0, 2);
  lcd.print("");
  lcd.setCursor(0, 3);
  lcd.print("");
}

void loop() {

  char key = keypad.getKey();
  if (key) {
    if (key == '#') {
      strcpy(str, "                ");
      lcd.setCursor(0, 3);
      lcd.print("CLEARED   SCREEN");
      delay(50);
      d = 0;
      str[d + 1] = '\0';
    }

    if (key != '#' and d < 16) {
      Serial.println(key);
      str[d] = key;
      str[d + 1] = '\0';
      Serial.println(d);
      if (d == 0) {
        lcd.setCursor(0, 3);
        lcd.print("                ");
      }
      lcd.setCursor(0, 3);
      lcd.print(str);
      Serial.print("will always be:");
      Serial.println(sizeof(str));
      Serial.println(str);
      Serial.print("Length of string :");
      Serial.println(strlen(str));
      d = d + 1;
    }
  }
}