Are the limits of for loops calculated once or with each loop?

Question

Is the limit in the following loop (12332*324234) calculated once or every time the loop runs?

for(int i=0; i<12332*324234;i++)
{
    //Do something!
}

Answer 1

For this it it calculated once, or more likely 0 times.

The compiler will optimize the multiplication away for you.

However this is not always the case if you have something like.

for(int i=0; i<someFunction();i++)
{
    //Do something!
}

Because the compiler is not always able to see what someFunction will return. So even if someFunction does return a constant value every time, if the compiler doesn't know that, it cannot optimize it.

EDIT: As MainMa said in a comment, you are in this situation you can eliminate the cost by doing something like this:

int limit = someFunction();
for(int i=0; i<limit ;i++)
{
    //Do something!
}

IF you are certain that the value of someFunction() will not change during the loop.