Re: [cc65] declaring variables after code

Hi all,

> I always try to avoid it in C code that I
> forgot that C99 actually allows it.

me too :)

to come back to the original question:

On many compilers it gives better results to declare all variables at
the beginning and not in nested blocks. This is because the stack frame
is extended and shrinked on block entries and exits. Look at this:

vars.c:
int main()
{
    int a;
    int c;
    int b = 3;

    for (a = 0; a < 3; ++a)
    {
        c = a + b;
        a = c + c;
    }
    return a;
}

vars2.c:
int main()
{
    int a;
    int b = 3;

    for (a = 0; a < 3; ++a)
    {
        int c;
        c = a + b;
        a = c + c;
    }
    return a;
}

skoe@akoya:~$ ls -la vars*
-rw-r--r-- 1 skoe skoe 1097 2010-04-23 21:18 vars
-rw-r--r-- 1 skoe skoe 1115 2010-04-23 21:15 vars2

In C the reasons to do this are rare. In C++ it may be useful if
constructors are involved, but that's a completely different language,
as Spiro told already.

Regards,

Thomas

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