Question

Haven’t used C++ in a while. I’ve been depending on my Java compiler to do optimization.

What’s is the most optimized way to do a for loop in C++? Or it is all the same now with moderm compilers? In the ‘old days’ there was a difference.

for (int i=1; i<=100; i++)

OR

int i;
for (i=1; i<=100; i++)

OR

int i = 1;
for ( ; i<=100; i++)

Is it the same in C?

EDIT:
Okay, so the overwhelming consensus is to use the first case and let the complier optimize with it if it want to.

Answer 1

I’d say that trivial things like this are probably optimized by the compiler, and you shouldn’t worry about them. The first option is the most readable, so you should use that.

EDIT: Adding what other answers said, there is also the difference that if you declare the variable in the loop initializer, it will stop to exist after the loop ends.