Post/Pre-Increment confusion

Question

From what I understand, if I have a variable k = 5, and I do ++k, the new value of k = 6. If I do k++, the value remains 5 until k appears the second time in the program, which is when it is changed to 6. For e.g:

k = 5;
System.out.println(k++); //prints 5, but now that k has appeared the second time, its value is incremented to 6
System.out.println(k); //prints 6

However, in this code:

class test {
    public static void main(String args[]){
        for(int i =0; i<10; i++){
            System.out.println(i);
        }
        int x = 0;
        x++;
        System.out.println(x);
    }
}

Output:

In the loop, though the variable i appears for the 2nd time(in System.out.println(i)), its value remains at 0. But for x, when it appears for the second time( in System.out.println(x); ) its value is incremented. Why? I'm confused about how post and pre-increment work.

Oh, yeah. "How do the post increment (i++) and pre increment (++i) operators work in Java?" already has the answer to my question. Sorry for posting. Can a moderator please delete this question? — User2956, Mar 22 '16 at 05:17
Sorry I marked as duplicate. Your question was actually about when the post increment happens in a for loop. — OneCricketeer, Mar 22 '16 at 05:27

Daniel Netto · Accepted Answer · 2016-03-28T04:49:58.277

1

For your code

    for(int i =0; i<10; i++){
        System.out.println(i);
    }

firstly the variable i is initialized to 0, it then checks if it satisfies the condition i < 10 and print the variable and lastly increments the variable i.

This is how the for loop works.

In the second piece of code you have written, it increments the variable x and lastly prints the value of x.

edited Mar 28 '16 at 04:49

answered Mar 22 '16 at 05:14

Daniel Netto

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Post/Pre-Increment confusion

1 Answers1