i have an error when messing with LCDs(expected primary-expression before '=' t)

#include <LiquidCrystal.h>

LiquidCrystal lcd (A0, A1, A2, A3, A4, A5);

void setup(){
  lcd.clear();
  lcd.begin(16, 2);
}

void loop(){
  lcd.setCursor(0, 0);
  lcd.print("***Zac Ahlers***");
  int digit = digitalRead(4);                //The error occurs here
  if (digit) = HIGH) {
    lcd.clear();
    lcd.print(*****SWITCH*****);
  }
}

= assigns a value == tests a value

(deleted)

....and a missing parenthesis.

if (digit) = HIGH) {