Lessons · Regex · capture groups
Capturing the parts
Parentheses group a piece of the pattern and remember what it matched, numbered from 1.
Hone is a place to practise programming. This is one of its lessons, written out in full and free to read without an account.
What it is for
Pulling year, month, day from a date or level and message from a log line.
How to think about it
Wrap each part you want back in parentheses. Use (?:...) for grouping you do not need to capture.
Worked example
pattern: (\w+)@(\w+)\.comTwo captures.
text: ada@example.comGroup 1 = ada, group 2 = example.
Your turn
Capture hours and minutes from 12:30.
(\d{2}):()Test a pattern against real text
The trap
Groups are numbered by the opening parenthesis, left to right, including nested ones.
Now you try
Next in Regex
Practise capture groups on HoneA question on it now, a coding challenge where there is one, and it is remembered for review. Free, no email needed.