RegexdrillCapture a standalone year
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
Capture the first standalone four-digit number on each line in group 1. Digits that are part of a longer number do not count. Lines without one give no match.
What this exercise teaches
\b(\d{4})\b captures four digits with a boundary on each side, so 12345 is skipped instead of yielding 1234.
A hint if you get stuck
Parentheses capture. \b marks a word boundary, the edge between a word character and a non-word character.
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