The assignment to variable has no effect?

Question

When I do this: count = ++count; Why do i get the warning - The assignment to variable count has no effect ? This means that count is incremented and then assigned to itself or something else ? Is it the same as just ++count ? What happens in count = count++; ? Why don't I get a warning for this ?

Answer 1

count++ and ++count are both short for count=count+1. The assignment is built in, so there's no point to assigning it again. The difference between count++ (also knows as postfix) and ++count (also known as prefix) is that ++count will happen before the rest of the line, and count++ will happen after the rest of the line.

If you were to take apart count=count++, you would end up with this:

    count = count;
    count = count+1;

Now you can see why postfix won't give you a warning: something is actually being changed at the end.

If you take apart count=++count, you would end up with this:

    count = count+1;
    count = count;

As you can see, the second line of code is useless, and that's why the compiler is warning you.