RegexdrillNested groups: a time and its hour
A regex exercise from Regexdrill. Solve it with a pattern box with live highlighting in your browser, checked against hidden test strings, and it is checked the moment you submit.
The task
Find the first time written HH:MM, with two digits on each side of the colon. Capture the whole time in group 1 and only the hours in group 2. Groups are numbered by their opening parenthesis, so the outer group comes first.
What this exercise teaches
In ((\d{2}):\d{2}) the outer parenthesis opens first, so it is group 1 and holds the whole time. The inner one opens second and is group 2. Counting opening parentheses from the left always gives the group number.
A hint if you get stuck
Put one pair of parentheses around the whole time, and a second pair inside it around the hours.
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