package pkg;

public class p43 {
	
	public static void main(String[] args) {
		int i=1;
		System.out.println("i="+i);
		
		i++;
		System.out.println("after i++,		i="+i);
		
		i=1;
		++i;
		System.out.println("let i=1,after ++i,then  i="+i);
		System.out.println("Above means: ++i OR i++,all can let i=i+1 after this instruction");
		
		i=1;
		int j=5,sum=0;
		sum=j+(++i);
		System.out.println("sum="+sum);//5+2
		System.out.println("i="+i);//i=2
		
		i=1;
		sum=0;
		sum=j+(i++);
		System.out.println("sum="+sum);//5+1
		System.out.println("i="+i);//i=2
		System.out.println("Above means: i++/i++  means access i but with different time to modify i's value");
		
		
	}
	
}


output：

i=1
after i++,		i=2
let i=1,after ++i,then  i=2
Above means: ++i OR i++,all can let i=i+1 after this instruction
sum=7
i=2
sum=6
i=2
Above means: i++/i++  means access i but with different time to modify i's value

i++：先访问存储变量i的内存并取值，返回取值并参与语句运算，然后让内存的值增加1；

++i：先让存储变量i的内存的值增加1，再访问内存并取值，返回取值结果参与语句运算。