How do I null a variable if its the value I return.

Ok i have this JASS trigger.

function JQK_Factor takes integer Card returns string
local string CurrentCard_String
if (Card == 11) then
set CurrentCard_String = "J"
else
endif
if ( Card == 12 ) then
set CurrentCard_String = "Q"
else
endif
if ( Card == 0 ) then
set CurrentCard_String = "K"
else
endif
if ( Card == 1 ) then
set CurrentCard_String = "A"
else
endif
return CurrentCard_String
set CurrentCard_String = null
endfunction

and when the trigger looks like this it gives me an error "Function must have a return value" or something like that. It works when I remove the last line "set CurrentCard_String = null"(but that causes memorly leaks) so I was wondering how do I null a variable that is the return value of the function? I mean I just can't have to put up with memory leaks do I?

Strangly enough when the last 3 lines look like this, It works.

return CurrentCard_String
set CurrentCard_String = null
return CurrentCard_String

but knowing how I had a problem before it makes me wonder if its nulling the variable or if it just returns the value then stops the function.

Well thanks in advance.

Well, in this particular case you could rewrite the function like this:
If you need to use a variable, you can use a global to hold the return value. Like this:

Thank you very much for your help, I tried that top example but it didnt pass the compiler either but i didnt add the return "" at the end is that neccesary? dont reply if you dont want I'll just try it out.

Obviously, a programmer would have figured out that this is an accessor method and has to have a return statement. Please learn programming before you make any more errors.