正则表达式优化：限制手机号格式并禁止10位重复数字

Let's break down why your original attempt didn't work, then build the correct regex that meets your requirements.

The Problem with Your Current Approach #

Your negated lookahead (?!.\1{10,}) is broken because:

• The \1 backreference refers to a capture group that doesn't exist yet when the lookahead runs. Lookaheads execute before the main pattern starts matching, so there's no captured value to reference here. That's why 111-111-1111 still matches—it's like the lookahead isn't even there.

The Correct Solution #

We need to adjust the lookahead to first isolate the digits in the phone number, then check if any digit repeats 10 or more times. Here's the final regex:

^(?!.*(\d)\1{9,})(1-)?\d{3}-\d{3}-\d{4}$

How This Works #

Let's break it down piece by piece:

1. Negated Lookahead: (?!.*(\d)\1{9,})
   • .* matches any characters (including the hyphens in your phone format) to skip past non-digit characters.
   • (\d) captures a single digit.
   • \1{9,} checks if that same digit repeats at least 9 more times (for a total of 10+ identical digits across the entire number).
   • If this pattern is found, the lookahead fails, and the entire regex rejects the phone number.
2. Main Phone Format Pattern: (1-)?\d{3}-\d{3}-\d{4}$
   • Keeps your original valid format rules: either nnn-nnn-nnnn or 1-nnn-nnn-nnnn.

Test Cases #

• Valid Matches:
  • 123-456-7890
  • 1-987-654-3210
• Invalid Matches (Blocked):
  • 111-111-1111 (10 identical digits)
  • 1-222-222-2222 (11 identical digits)
  • 333-333-3333 (10 identical digits)

Key Takeaway #

When using backreferences in lookaheads, make sure the capture group is defined inside the lookahead (or the lookahead can access it). Your original attempt tried to reference a capture group from the main pattern before it was ever captured, which is why it didn't work.

内容的提问来源于stack exchange，提问作者RedAuerbach