Why is the Compiler warning that variable may not be initialized?

问题

I am getting a compiler warning I don't understand:

procedure Test;
var
  Var1: Integer;
begin
    while True do
    begin
        try
            if System.Random > 0.5 then
            begin
                ShowMessage('Skipping');
                continue; // If I remove this line, the warning goes away
            end;
            Var1:=6;
        except on
            E:Exception do
            begin
                ShowMessage('Error');
                raise;
            end;
        end;
        ShowMessage(IntToStr(Var1)); // Compiler warning on this line
    end;
end;

When I compile this in Delphi 2010 I get:

[DCC Warning] OnlineClaimManagerMainU.pas(554): W1036 Variable 'Var1' might not have been initialized

If I remove the call to 'continue', the warning goes away.

Also, if I remove the try/except clause (and leave the continue), the warning goes away.

How will execution get to the line in question without Var1 being initialised?

回答1:

Var1 will always be initialised before it is used. The compiler gets confused by try-except handling: your code is too complex for the compiler to be able to actually determine that Var1 is always initialised. It sees there may be a handled exception before Var1:=6;, which would leave Var1 uninitialised, but it doesn't see that that exception will always be re-raised.

回答2:

You should but the ShowMessage(IntToStr(Var1)); into the try except block. Then it should be clear to the compiler, that Var1 is intialized and looks more as clean code.

回答3:

It is a farily good warning. What it tells that you do not assign any value to the variable which may be used somewhere else in your code. Warning also tells that if it's used then the value assigned to it may be not what you expect.

来源：https://stackoverflow.com/questions/11554857/why-is-the-compiler-warning-that-variable-may-not-be-initialized

标签

Delphi

delphi-2010