What is the difference between x++ and ++x in Java

Question

What is the difference between x++ and ++x in Java

Can anybody please tell me the difference of the above by refering the below code,

class Example{
    public static void main(String args[]){
        int x=10;
        int y;
        y=x++;  //Prints 11     10 
        System.out.println(x+"\t"+y)
    }
}

class Example{
    public static void main(String args[]){
        int x=10;
        int y;
        y=++x;  //Prints 11     11 
        System.out.println(x+"\t"+y)
    }
}

@SotiriosDelimanolis Not necessarily, if you don't know it's called *postincrement* and *preincrement*, respectively. Easy if you know. Still a duplicate, this has been asked many times. — user, Feb 26 '13 at 15:30
@MichaelKjörling You don't need to call it by name though. Just put i++ vs ++i in some search engine. — Sotirios Delimanolis, Feb 26 '13 at 15:31
@MichaelKjörling Actually its very easy, check this [google search](https://www.google.co.uk/#hl=en&output=search&sclient=psy-ab&q=difference+between+x%2B%2B+and+%2B%2Bx+java&oq=difference+between+x%2B%2B+and+%2B%2Bx+java&gs_l=hp.3...766.10380.0.10500.39.20.2.17.18.0.247.2664.0j18j1.19.0.les%3B..0.0...1c.1.4.psy-ab.r_6b-1uvjYI&pbx=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.&bvm=bv.42965579,d.d2k&fp=2d067e3b3a7f4d22&biw=1280&bih=923) — Abdusalam Ben Haj, Feb 26 '13 at 15:31

score 3 · Answer 1 · answered Feb 26 '13 at 15:30

3

y=x++ assigns x to y, then increments x.

y=++x increments x, and then assigns it to y.

answered Feb 26 '13 at 15:30

xlecoustillier

16,183
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score 2 · Answer 2 · answered Feb 26 '13 at 15:30

2

++x is the pre-increment. i.e., The value of x is first incremented and then assigned to x.

x++ is post increment. i.e., the value of x is assigned first and then incremented.

y=x++;

is essentially same as

y =x;
x= x+1;

y=++x; is same as

y= (x+1);

answered Feb 26 '13 at 15:30

PermGenError

45,977
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@MichaelKjörling sorry, i dint get you. why would you reassign y to x?? – PermGenError Feb 26 '13 at 15:43

score 0 · Answer 3 · answered Feb 26 '13 at 15:30

0

Pre and Post increment. Increment BEFORE assignment and increment AFTER assignment respectively.

answered Feb 26 '13 at 15:30

Louis Ricci

20,804
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score 0 · Answer 4 · answered Feb 26 '13 at 15:41

The difference is that in the first case (x++) Java first resolves the assignment issue and then increments x. In the other case (++x) Java first resolves the increment and then the assignment. In the following code you will see the difference:

@Test
public void test1() {
    int x = 1;
    int y = 1;

    y = 2 + x++;
    assertEquals(2, x);
    assertEquals(3, y);
}

@Test
public void test2() {
    int x = 1;
    int y = 1;

    y = 2 + ++x;
    assertEquals(2, x);
    assertEquals(4, y);
}

As you can see, x always will be incremented, but the difference is the order in which the expression is resolved.

Hope it would be useful!

What is the difference between x++ and ++x in Java

What is the difference between x++ and ++x in Java

4 Answers4