What is more efficient, i++ or ++i? [duplicate]

Solution 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.

Solution 2:

I would look elsewhere for optimization potential.

Solution 3:

Efficiency shouldn't be your concern: it is meaning. The two are not the same, unless they are freestanding: one operates pre-use of the value, the other post.

int i; i = 1; cout << i++; //Returns 1

int i; i = 1; cout << ++i; //Returns 2

When meaning isn't important, most compilers will translate both ++i and i++ (say in a for loop) into the same machine/VM code.