Question

I am confused about the regular expression below. Please help me to understand it.

my $test = "fred andor berry";
if ($test =~ /fred (and|or) berry/) {
    print "Matched!\n";
} else {
      print "Did not match!\n";
}

I thought it would match, but I get “Did not match!”. If I add + in it, like this,

my $test = "fred andor berry";
if ($test =~ /fred (and|or)+ berry/) {
   print "Matched!\n";
} else {
   print "Did not match!\n";
}

Then it matches. I thought I can use and|or to match an expression with “and”, “or” and “andor”. No?

Answer 1

The expression (and|or) will match and or or, but not andor. When you add the +, it will accept two (actually one or more) consecutive matches of the same pattern, which allows it to match andor. (First it matches and, then or.)