What is more efficient, i++ or ++i?

Question

Exact Duplicate: Is there a performance difference between i++ and ++i in C++?
Exact Duplicate: Difference between i++ and ++i in a loop?

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What is more efficient, i++ or ++i?

I have only used this in Java and C/C++, but I am really asking for all languages that this is implemented in.

In college I had a professor show us that ++i was more efficient, but it has been a couple of years, and I would like to get input from the Stack Overflow community.

Answer 1

i++ :

• create a temporary copy of i
• increment i
• return the temporary copy

++i :

• increment i
• return i

With optimizations on, it is quite possible that the resulting assembly is identical, however ++i is more efficient.

edit : keep in mind that in C++, i may be whatever object that support the prefix and postfix ++ operator. For complex objects, the temporary copy cost is non negligible.