If statements inside or outside loops?

Question

Is it better if I do this:

foreach my $item ( @array ) {
   if ( $bool ) {
     .. code ..
   }
   else {
     .. code ..
   }
}

or

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Answer 1

Simply evaluating a boolean variable as you have done here, these are roughly equivalent. However, if the variable were replaced with a complicated expression that took a long time to evaluate, the second example would be better because it would only be evaluated once.