- What does \d stand for if used in a Perl regular expression?
- What does the operator =~ mean if used in a Perl expression,
such as $a =~ /World/;.
- If I want to perform a substitution in a Perl expression, what operator
will I use (e.g., in the expression $a =~ ?/a/b/;, what replaces
- How can I write a regular expression to show that I want 0 or more
repetitions of the character 'a'?