Why does local variable inside foreach loop conflict with variable declared outside the loop?

Question

Given this code:

List things = new List();

foreach (string thing in things)
{
    string foo = thing.ToUpper();
}

string foo =          


        

Answer 1

While you can only refer to the outer foo after you declared it, locals are allocated at the beginning of a function which means the inner foo will overshadow the outer one, even if it hasn't been declared yet.