Which method of incrementing should I use in C#? ++i or i++?

Question

E.g.

for (int i = 0; i < 10; ++i) 
...

vs

for (int i = 0; i < 10; i++) ...

I have been told ++i would be more efficient. Are there differences in other languages such as JavaScript or is it a more fundamental rule?

in that case `i++` is the same as `++i` ... main difference between them is post- versus pre-incrementation — Kamil Budziewski, Sep 25 '13 at 10:43
Been asked a million times and discussed ad nauseum since Scott Meyers wrote "Effective C++". C'mon. — duffymo, Sep 25 '13 at 10:45
http://stackoverflow.com/questions/3346450/what-is-the-difference-between-i-and-i — Lev, Sep 25 '13 at 10:45

score 4 · Accepted Answer · answered Sep 25 '13 at 10:45

The difference between i++ and ++i is the value of the expression.

The value i++ is the value of i before the increment. The value of ++i is the value of i after the increment.

However in your loop it does not make any difference.

int i = 0;
00000088  xor         edx,edx 
0000008a  mov         dword ptr [ebp-40h],edx 
            i++;
0000008d  inc         dword ptr [ebp-40h] 
            ++i;
00000090  inc         dword ptr [ebp-40h]

score 2 · Answer 2 · edited May 23 '17 at 10:25

for(int i=0;i<10;i++)
{
 //some jobs
}

is the same as:

int i=0;
while(i<10)
{
 //some jobs
   i++;
}

and

for(int i=0;i<10;i++)
{
 //some jobs
}

equals to:

int i=0;
while(i<10)
{
 //some jobs
   ++i;
}

so no difference here, performance will be the same

i++ is postincrementation and ++i is preincrementation, so there is a difference in other cases but not performance. You can read more about pre and post incrementation here C# Pre- & Post Increment confusions

score 0 · Answer 3 · answered Sep 25 '13 at 10:45

0

The advantage of using ++i in some languages is that it does not create a temporary unnecessarily (see e.g. Exceptional C++ for a thorough explanation for C++).

answered Sep 25 '13 at 10:45

Mikael Call

75
1
8

score 0 · Answer 4 · answered Sep 25 '13 at 10:51

++i is no more efficient than i++ in C# if you are not assigning the result in the same expression. The same code is generated for both cases.

Of course, if you assign the result to something in the same expression, there will be a difference in the code generated - but in that event, the semantics are different and you don't have a choice of which form of increment to use.

So use whichever you like best.

Which method of incrementing should I use in C#? ++i or i++?

4 Answers4