"Types of actual and formal var parameters must be identical" error in Procedure

delphi procedure
Alper picture Alper · Dec 10, 2010 · Viewed 13.5k times · Source

I am trying to write a procedure in delphi. This procedure gets the name of TControl descendent element and then try to change some properties. But when i try to do it, Delphi gives an error like:

E2033 Types of actual and formal var parameters must be identical

Procedure:

procedure Change_prop(var Control: TControl;height:integer;width:integer);
begin
//......
end;

Usage Example : Change_prop(Label1, 50,200); What can be the solution of that error..Thanks.

Answer

David Heffernan picture David Heffernan · Dec 10, 2010

You just need to remove the var in the Control parameter and make it a value parameter. Because Delphi objects are actually implemented as reference types, you can call methods on them, change member fields etc. even if you pass them to a procedure as a value or const parameter.

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