Because you do not test if the variable is defined but if it is true or false (0, undef, "").

Maybe you had something like this in mind? 

sub isDef {
 return (defined shift) ? 'true' : 'false';
}

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In reply to Re: Validation: is defined whether the variable? by Perlbotics
in thread Validation: is defined whether the variable? by breeze

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