c++ - Definition of variable inside loop

I was looking for an answer for my questions on many pages but I
couldn't find it.

In this case we are defining
variable and reinitialaze it in every
loop:

while(1)
int
            k = 7;

In this case we
are defining variable before the loop and reinitialaze it in every loop.

int
            k;
while(1)
k =
            7;

There is
any advantages or disadvantages of using both methods? Or maybe it don't make a
difference?

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class="normal">Answer

The
difference is in terms of scope of the
variable.

In the first case, once the
while loop ends, the variable k cannot
be accessed.

In the second case, the variable
k can be accessed out of the while
loop.

In both cases, the variable is defined on
the stack (or as TartanLlama points out, they could be allocated in registers) and so
there is no difference in terms of performance.

However, the example you've used is
wrong in the case that the while loop will never end. I'm
guessing this is just a piece of dummy code to explain the situation.