#include <LiquidCrystal.h>

const byte  rs = 12;
const byte en = 11;
const byte d4 = 5;
const byte d5 = 4;
const byte d6 = 3;
const byte d7 = 2;

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

int ButtonPin = 10;
int ButtonVal = 0;

void setup() {
  pinMode(ButtonPin, INPUT_PULLUP);
  lcd.begin(16, 2);   // set up the LCD's number of columns and rows
}

void loop() {
  ButtonVal = digitalRead(ButtonPin);

  if (ButtonVal == LOW) {
    lcd.setCursor(0, 0);     // set the cursor to column 0, line 0
    //                  10        20        30        40        50        60        70        80
    //         012345678901234567890123456789012345678901234567890123456789012345678901234567890
    //lcd.print("Really long message to display0123456789");
    //         1234567890
    lcd.print("          Really long message to display");    // scroll "n" positions (string length) to the left to move it offscreen left:
    for (int positionCounter = 0; positionCounter < 30; positionCounter++) {
      delay(250);       // wait a bit
      lcd.scrollDisplayLeft();
    }
    lcd.clear();
  }
}