Output only parameters (extracted from Delphi basic)

		we can go further, and define parameters that we can update, but which are there for update only-output from our subroutine. they shocould not be read by the subroutine, the caller not responsible for any starting value they might contain.
		procedure doit (out a: integer); begin : = 123; showmessagefmt ('a in the procedure = % d', [a]); end; procedure tform1.formcreate (Sender: tobject ); var A: integer; begin showmessage ('a before the call is unknown '); // call the procedure doit (a); showmessagefmt ('a in program now = % d', [a]); end;
		A before the call is unknown A In the procedure = 123 A In program now = 123
	Constant Value Parameters
		For code clarity, and performance, it is often wise to declare arguments that are only ever read by a subroutine as constants. This is done withConstPrefix. It can be used even when a non-constant parameter is passed. It simply means that the parameter is only ever read by the subroutine.
		procedure doit (const A: integer; out B: integer ); begin B: = A * 2; end; procedure tform1.formcreate (Sender: tobject ); var A, B: integer; begin A: = 22; // call the procedure doit (a, B); showmessagefmt ('B has been set to = % d', [B]); end;
		B has been set to 44
		Notice that when defining two argument types, the arguments are separated with;.