Many languages allow regex to be enclosed or delimited between a couple of specific characters, usually the forward slash
Delimiters have an impact on escaping: if the delimiter is
/ and the regex needs to look for
/ literals, then the forward slash must be escaped before it can be a literal (
Excessive escaping harms readability, so it's important to consider the available options:
Perl, for example, allows almost anything to be a delimiter. Even Arabic characters:
$str =~ m ش ش
Specific rules are mentioned in Perl's documentation.
PCRE allows two types of delimiters: matched delimiters and bracket-style delimiters. Matched delimiters make use of a single character's pair, while bracket-style delimiters make use of a couple of characters which represents an opening and closing pair.