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delphioperatorsdelphi-2007variant

Why "=" operator results True when comparing varEmpty with a zero evalued varInteger?

Why does the = operator results True when comparing a varEmpty Variant variable with a zero evalued varInteger Variant variable?

var
  V1 : Variant;
  V2 : Variant;
begin
  V2 := 0;
  if(V1 = V2)
  then ShowMessage('V1 = V2')
  else ShowMessage('V1 <> V2');
end;

This code produces the following output:

V1 = V2

Does the equality operator = only checks the value part of Variant variables?

Solution

  • In order to make a comparison, the empty variant is converted to an integer. According to the variant type conversion rules, the unassigned (empty) variant is converted to 0. Hence the expression returns true.