7.20 Special Parameters

• Untyped reference parameters can be denoted by

            procedure Foo (var x);
       

  like in Borland Pascal. In GNU Pascal, you can also use

            procedure Foo (var x: Void);
       

• GNU Pascal defines ellipsis parameters for variable argument lists:

            procedure Foo (a: Integer; ...);
       

  However, GPC does not (yet) provide a portable mechanism to access the additional arguments.

• Structured function result types: According to Extended Pascal, GNU Pascal allows functions to return records and arrays.
• BP style open array parameters

            procedure Foo (a: array of Integer);
       

  are implemented. However, Standard Pascal conformant array parameters are usually a cleaner mechanism to pass arrays of variable size.

• Besides BP compatible procedural types and procedure pointers (see BP Procedural Types), GNU Pascal supports Standard Pascal's procedural parameters:

            procedure DrawGraph (function f (x: Real): Real);