Reinitializing variables & their speed sacrifice

[nbaztec]

My C++ teacher states that one should not initialize a variable at declaration time (yes i know who made her a teacher!?). Although I'm past the C# point, & VCL, & GDI in C/C++, I find this amusing & irritating at the same time.

so for the foll. code:

//It's C Code, so cant initialize 'a' inside loop.
int main()
{
	int a=0,b=0;
	scanf(...,&b)
	for(a=0;a<10;a++)
		...	
return 1;
}

She says:
1. Why the hell use int main() when void main() works fine. Let's just not get started on her ignorance to good coding practices & her ignorance to OS's error handling. I just skip it thinking she's ignorant.

2. Why initialize b. When b is inputted. ***?
3. Why initialize a, when you reinitialize it in loop. *** x2?

OK, as we all know it's ALWAYS a good practice to ZeroMemory() or atleast initialize a variable to 0 or NULL. Her only case may appear a bit(0.001&#37 effective, if this practice poses a speed loss?

Only if assigning a=0 inside loop or declaring b=0 at initialization poses speed loss, then only her arguments might be only a bit(0.001%) effective, otherwise I'll declare war.

Can anyone tell if these practices do really pose a speed issue?

Thanks,
Nisheeth