public class Demo{ public static void main(String [] args){ int num=2; System.out.println(num++);//后置加加,先打印后加 2 System.out.println(num); System.out.println(++num);//前置加加,先加后打印 4 System.out.println(num); int num1=4; int result=num1++;//先赋值给result后num自