http://qs1969.pair.com?node_id=946

if statements test a control statement to see whether it is true or false. else and elsif clauses can also be tagged on the back.
#your basic if if($value==1){ print "value is equal to 1\n"; } #your basic if/else if($value==1){ print "value is equal to 1\n"; } else{ print "value is not equal to 1\n"; } #your basic if/elsif/else if($value==1){ print "value is equal to 1\n"; } elsif($value==2){ print "value is equal to 2\n"; } elsif($value==3){ print "value is equal to 3\n"; } else{ print "value is not equal to 1,2, or 3\n"; }
Unless statements offer you the opposite functionality. If the control statement evaluates to false then the statements inside the block are executed.