Function

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Overview

A function is a declaration of a routine which may be invoked

• from within the unit that declares it
• from outside the unit if the function is public,
• or from within a program

The routine returns a value as part of its definition. A routine that does not return a value as part of its definition is a procedure.

A function which is part of an object is called a property and can be assigned/return a value (if you can't assign a value, it would be a method)

Function parameters

• Call by value
• Variable parameter (call by reference)
• Out parameter
• Const parameter
• Default parameter
• Open array parameters
• Array of const

Examples

Addition of two integers example:

 function add(c1, c2 : integer) : integer;
 begin
 add := c1 + c2; //or use result := in Object Pascal/Delphi mode
 end;

 var 
   total: integer;

 begin
   total := add(4, 5);
   writeln (total); // result is 9
 end.