Unpredicted language behavior i++

Question

I tried to do the following

i=0;
if (i++ % Max_Col_items == 0 && i !=0)
{

}

and discovered that it increased i in the middle

i % Max_Col_items == 0;
i=i+1;
i !=0;

when I though it would add increase i in the end:

i % Max_Col_items == 0;
i !=0;
i=i+1;

Can any one find explanation of how i++ works in C#?

possible duplicate of [What's the difference between X = X++; vs X++;?](http://stackoverflow.com/questions/226002/whats-the-difference-between-x-x-vs-x) — nawfal, Jul 20 '14 at 08:09

score 3 · Accepted Answer · edited May 23 '17 at 12:04

3

i++ will give you the original value, not the incremented, You will see the change on the next usage of i. If you want to get the incremented value then use ++i.

See the detailed answer by Eric Lippert on the same issue

edited May 23 '17 at 12:04

Community

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answered Dec 03 '12 at 10:34

Habib

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The OP has made it clear what he expected to happen and what he has observed happening. He doesn't _want_ the incremented value; he wants to know why the value is incremented by the second part of his `&&`. – Rawling Dec 03 '12 at 10:39
@Rawling, thats what I said, Change will be visible on the next usage of `i` – Habib Dec 03 '12 at 10:41
Eventually, yes. Your original answer just said that `i++` gives the original value and use `++i` if you want the original value, which was irrelevant to the question. – Rawling Dec 03 '12 at 10:43
@Rawling, I was in the middle of editing and trying to find the answer by Eric lippert, but thats ok – Habib Dec 03 '12 at 10:45

score 0 · Answer 2 · answered Dec 03 '12 at 10:36

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i++ immediately increments the value of i but evaluates as the value before incrementation.

It doesn't leave the value of i untouched until the end of the line of code, which appears to be what you expect.

answered Dec 03 '12 at 10:36

Rawling

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score 0 · Answer 3 · answered Dec 03 '12 at 10:49

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That is because (as you have rightly noted)

i % Max_Col_items == 0;

is an operation in itself. Once that line of operation is over (with value of i ) the increment is done.

answered Dec 03 '12 at 10:49

Milind Thakkar

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Unpredicted language behavior i++

3 Answers3