10.5. The elsif Clause

Every so often, you may need to check a number of conditional expressions, one after another, to see which one of them is true. This can be done with the if control structure's elsif clause, as in this example:

    if ( ! defined $dino) {
      print "The value is undef.\n";
    } elsif ($dino =~ /^-?\d+\.?$/) {
      print "The value is an integer.\n";
    } elsif ($dino =~ /^-?\d*\.\d+$/) {
      print "The value is a _simple_ floating-point number.\n";
    } elsif ($dino eq '') {
      print "The value is the empty string.\n";
    } else {
      print "The value is the string '$dino'.\n";
    }