C# lifetime of a variable in try finally

Question

i got the following code

why has x in the finally-block the value 5 instead of beeing "already defined" or having the default value 0?

Answer 1

The lifetime of x is within {...} block, try in your case; however, since there's no zero-initialization of local variables in .Net the next x contains trash which is former x value

try
{
   int x = 5;
}
finally
{
   // x is re-declared; since x is local it contains trash;
   // former x was aquired at the stack, so .Net just moves stack pointer 
   // and doesn't remove former x value
   int x; 
   ...
}

http://msdn.microsoft.com/en-us/library/aa691170(v=vs.71).aspx

...A local variable is not automatically initialized and thus has no default value...

http://msdn.microsoft.com/en-us/library/aa664742(v=vs.71).aspx

...The scope of a local variable declared in a local-variable-declaration is the block in which the declaration occurs...

Answer 2

I guess you have set a breakpoint in the finally and looked at x. x has no value according to the C# language spec but the debugger probably looked at the storage location that the first x had and showed you its value.

In real code you would be unable to read from x in the finally.

The debugger does not obey the rules of the language.