How do named and unnamed PCRE capturing groups interact?

Question

If the regular expression is e.g. ^(?<object>[\-\w]+)/([\-\w]+)$, will one invoke the second capturing group as $2 or as $1? In other words, are anonymous capturing groups absolutely or relatively numbered?

Answer 1

Use $2 to refer to the second numbered capturing group. Note I would not call it anonymous, maybe, "unnamed" would suit better here.

See a sample regex demo.

See PCRE docs:

PCRE supports the use of named as well as numbered capturing parentheses. The names are just an additional way of identifying the parentheses, which still acquire numbers.