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Gambas dal mondo esterno => Mailing List => Topic aperto da: vuott - 06 Ottobre 2014, 01:25:28

Titolo: Usare AND ed OR nello stesso test logico
Inserito da: vuott - 06 Ottobre 2014, 01:25:28

Vi riporto questa discussione:


" Why is it not allowed to use AND and OR in the same logical test?

Jørn "


" It is allowed and works:

  $ gbx3 -e "(False And Not False) Or (False Or Not False)"
  True

Maybe you refer to the AND IF and OR IF keywords in an IF statement?

Regards,
Tobi "


" Aha, yes you're right :) Removing an extra IF that had sneaked in was
the solution.

Jørn "


" The extra "if" enables short-circuiting
http://en.wikipedia.org/wiki/Short-circuit_evaluation
and thus it is very useful in some cases.

Example, you can write "if then" structures like this:

Codice: gambas [Seleziona]

If hObject <> Null And If hObject.SomeProperty = True Then

Without the extra "if" this would fail, if the hObject would be null.

Jussi "