++i vs i++ ... what's the difference?

This might be dumb question, but can someone tell me what is the difference? I read somewhere that when your evaluating something if you use ++i, "i" is increased then function is evaluated, but if you use i++, function is evaluated then "i" is increased.

But when I ran this:

Code:

int n = 0;
for (int i = 0; i < 10; ++i)
{
	n++;
	std::cout << n << ". " << i << std::endl;
}

and this:

Code:

int n = 0;
for (int i = 0; i < 10; i++)
{
	++n;
	std::cout << n << ". " << i << std::endl;
}

in both cases I get:

Code:

1. 0
2. 1
3. 2
4. 3
5. 4
6. 5
7. 6
8. 7
9. 8
10. 9

So what is the difference?
Don't know if that makes any difference but this is run on Visual Studio 2005

Originally Posted by ranko_6

This might be dumb question, but can someone tell me what is the difference? I read somewhere that when your evaluating something if you use ++i, "i" is increased then function is evaluated, but if you use i++, function is evaluated then "i" is increased.

Your understanding is correct.

But when I ran this:
in both cases I get:

Code:

1. 0
2. 1
3. 2
4. 3
5. 4
6. 5
7. 6
8. 7
9. 8
10. 9

Since the ++ operators are in their own, self-contained statements, it makes no difference.

The difference between prefix (++x) and postfix (x++) only matters if you actually use the value, like this.

Code:

y = array[x++];
z = ++x;

As brewbuck said, if it's by itself in a statement unto itself as you have it then there's no difference.

Thanks for info, tried with "if" statement and it worked.

The ++ operators also work with some class types (like iterators). In some cases it can be more efficient to use ++i instead of i++ when you aren't using the return value. Because of that, and because almost all other factors are equal, many people prefer to use ++i over i++ when the return value is not used.