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

Question

Given this code:

List<string> things = new List<string>();

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

string foo = String.Empty;

Why does the compiler complain that foo is declared twice? Surely the instance declared in the foreach loop is only valid within the scope of the loop?

blogs.msdn.com/b/ericlippert/archive/tags/declaration+spaces — CodesInChaos
– CodesInChaos, Commented Mar 23, 2012 at 9:54
I think your argument breaks down when you consider variable capture — David Heffernan
– David Heffernan, Commented Mar 23, 2012 at 9:56
There are at least half a dozen duplicates of this question. One example: How does .NET handle variables inside scope — CodesInChaos
– CodesInChaos, Commented Mar 23, 2012 at 9:56

Joey · Accepted Answer · 2012-03-23 09:55:43Z

5

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.

answered Mar 23, 2012 at 9:55

Joey

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