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Categories / Delphi / Compiler Directives
 

Out - identifies a routine parameter for output only

Routine name(... Out OutputVarName : type; ...) Description The Out directive identifies a function or procedure parameter as being a variable reference for outputting to only. It allows a routine to return data to a variable of caller in addition to the Result value available in functions. It is equivalent to Var except that the value should not be changed by the routine. Delphi does not seem to enforce this, nor does it seem to enforce the need to assign a value. Related commands Const Starts the definition of fixed data values Function Defines a subroutine that returns a value Procedure Defines a subroutine that does not return a value Var Starts the definition of a section of data variables Example code : Demonstrate all three types of parameter handling var number1, number2, number3 : Integer; begin // Put values in our numbers number1 := 3; number2 := 4; number3 := 5; // Call the simple routine to see how they are handled ThreeParms(number1, number2, number3); // Show their values now ShowMessageFmt('number1 = %d number2 = %d number3 = %d ', [number1, number2, number3]); end; // Simple routine illustrating 3 types of parameter handling // value1 : Input value only // value2 : Output value only // value3 : Input and output value procedure TForm1.ThreeParms( value1: Integer; Out value2: Integer; var value3: Integer); begin // Add value1 to value 3 as the value2 output value2 := value1 + value3; // Multiply value1 by value3 to give value3 output value3 := value1 * value3; end; Show full unit code value1 = 3 value2 = 8 value3 = 15