Why doesn't x increment after x++?

Question

Possible Duplicate:
What is x after “x = x++”?

In a loop I have:

int x = 0;
while(int x < 10){
x = x++;
}

Why does this not work?

By "not work" I'm guessing you mean "x never changes from 0". Is that correct? — Bob Kaufman, Nov 10 '11 at 18:33

score 3 · Answer 1 · answered Nov 10 '11 at 18:34

3

Change x = x++ to just x++. x++ is unary operation and you don't need to use the assignment operation.

answered Nov 10 '11 at 18:34

Kurtis Nusbaum

score 3 · Answer 2 · answered Nov 10 '11 at 18:35

3

Post increment operator uses the value first and then increments.

x=x++;

Here, we assign X to X (zero to zero) and then we increment X to 1 but we never assign it to anything.

you can change to

X=++X;

and this should give you what you want.

answered Nov 10 '11 at 18:35

Mechkov

2

I disagree with `X=++X`, I think `x = x + 1` or `x++` is a lot clearer! – Johan Sjöberg Nov 10 '11 at 18:38
I'm not sure what you mean by "we never assign it to anything". ++ acts on the variable itself. – Bob Kaufman Nov 10 '11 at 18:39
1

it is all about the preference man. X=++X; is used to show the difference between post and pre increment operators. So, i answered the question by providing extra info on an operator which is related to the topic. – Mechkov Nov 10 '11 at 18:40
@Bob Kaufman it means the assignment takes precedence over the increment. And X is never incremented in our case (x=x++) – Mechkov Nov 10 '11 at 18:45
Somehow I managed to miss that. Thanks! – Bob Kaufman Nov 10 '11 at 19:05
Well, maybe my wording were confusing. No problem! Regards! – Mechkov Nov 10 '11 at 19:06

score 1 · Accepted Answer · answered Nov 10 '11 at 18:34

1

Well... try this instead.

int x = 0;
while(int x < 10){
x++;
}

answered Nov 10 '11 at 18:34

Gabriel

score 1 · Answer 4 · answered Nov 10 '11 at 18:35

1

Try converting

x = x++;

to

y = x++; // i.e. y = x, then increment x
x = y;

to understand it.

answered Nov 10 '11 at 18:35

Ed Heal

4 Answers4