regex - What does ?: in a regular expression mean? -

regex - What does ?: in a regular expression mean? -

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reference - regex mean? 1 reply

please explain meaning of regular look , groups look generate?

$string =~ m/^(\d*)(?: \d.*?)(\d*)$/

ps: i'm re-factoring perl code java.

it means not capturing group. after successful match first (\d*) captured in $1, , sec in $2, , (?: \d.*?) not captured @ all.

$string =~ m/^(\d*)(?: \d.*?)(\d*)$/

from perldoc perlretut

non-capturing groupings

a grouping required bundle set of alternatives may or may not useful capturing group. if isn't, creates superfluous add-on set of available capture grouping values, within outside regexp. non-capturing groupings, denoted (?:regexp), still allow regexp treated single unit, don't found capturing grouping @ same time.

regex perl regex-group