Course of Raku / Regexes and grammars / Regexes / Adverbs

Case-insensitive matching

Normally a regex distinguishes upper-case from lower-case letters: /hello/ does not match HELLO. The :i adverb (short for :ignorecase) turns that distinction off:

say 'HELLO' ~~ /:i hello/; # ｢HELLO｣

With :i, the letters match regardless of case, so the lower-case pattern matches the upper-case text. It works in either direction and for mixed case too:

say 'I use RAKU' ~~ /:i raku/; # ｢RAKU｣

You can also write the adverb on the m/// operator instead of inside the pattern:

say 'HELLO' ~~ m:i/hello/; # ｢HELLO｣

Both of these make the whole pattern ignore case. The next page looks more closely at where an adverb applies — the difference between the two placements — and how to switch case-sensitivity back on for part of a pattern.

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← Adverbs   |   Quiz — Ignorecase →

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