in Chapter 6, with Tiger and Xcode 2.1, I noticed that an "i++" or a "++i" in a "for" loop produce the same result.
Is it usual ?
I believed before that "++i" produced incrementation before execution of instructions between braces, and "i++" produced incrementation after instructions between braces.
Was I wrong ?
Is it a preprocessor specificity ?

FJ

__________________
FJ

I am ashamed of my question, and I prefer be answering myself.
No importance "i++" or "++i". I was wrong.
The block of instructions during the loop is executed before the incrementation of "i", so pre-incrementation or post-incrementation has no importance.

Please, excuse me.

FJ

Logically in a for-loop it doesn't matter. The expression is evaluated after the conditional code is run.

Some programmers claim using "++i" instead of "i++" reduces in smaller object code (i.e., number of machine instructions generated by the compiler) and is often more accurately what you meant to say. I don't know if that's true or not, and if it were true, the few bytes saved doesn't seem all that significant to me. But that's a matter of opinion.

The difference in efficiency probably won't be noticeable with variables like integers, but if you are incrementing an instance of a (custom) class it may be. The difference will be that post increment will make a copy (thus calling the possibly rather expensive copy constructor) of itself before executing the increment and then return that copy. With pre increment this copy instruction isn't needed.