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[SayeyeZohor]

uses Variants;



procedure VariantDemo;

var

  vDemo: Variant;

  bTest: Boolean;

begin

  // EMPTY

  vDemo := Unassigned;          // assign EMPTY to variant

  bTest := VarIsEmpty(vDemo);   // check if variant is EMPTY

  // NULL

  vDemo := NULL;                // assign NULL to variant

  bTest := VarIsNull(vDemo);    // check if variant is NULL

  // numeric

  vDemo := 8.8;                 // assign a float to variant

  bTest := VarIsNumeric(vDemo); // check if variant is numeric

  // text

  vDemo := 'demo';              // assign a string to variant

  bTest := VarIsStr(vDemo);     // check if variant contains text

  // COM methods can define obtional parameters. if you are

  // working with typelibraries you have to pass a parameter

  // nevertheless, then you can pass "EmptyParam"

  vDemo := EmptyParam;

  bTest := VarIsEmptyParam(vDemo);

end;