RegexdrillNormalize phone numbers
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
Each line is one ten-digit US phone number in one of these shapes: (555) 123-4567, 555-123-4567, 555.123.4567, 555 123 4567 or 5551234567. Rewrite every line as 555-123-4567: three digits, a hyphen, three digits, a hyphen and four digits.
What this exercise teaches
\(?(\d{3})\)?[ .-]?(\d{3})[ .-]?(\d{4}) with the replacement $1-$2-$3 captures the digits whatever sits between them. Deleting every non-digit would also remove the hyphens the output needs.
A hint if you get stuck
Capture the three digit groups and make the parentheses and the separator between groups optional. Write the hyphens in the replacement.
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