正则表达式-查找多个匹配项

Question

I have following 1010159552597 and I would like to find the numbers that start with 10, followed by 1 or 0 and ending with 7 digits. I use following RegEx to search

(10[01][0-9]{7})

Following result is given: 1010159552

But I also would have expected the following: 1015955259

How can I manage to get both results?

Thanks

Answer 1

Regular expressions consume characters and don't go back over previous matches. A way around this is to use zero-length assertions (see code below) to capture what you want.

Code

See regex in use here

(?=(10[01]\d{7}))

Results are in capture group 1:

• 1010159552
• 1015955259

---

Explanation

• (?=(10[01]\\d{7})) Positive lookahead ensuring what follows matches
  • (10[01]\\d{7}) Capture your original expression into capture group 1

Answer 2

You're right in that your expectation does match your regex, however, it will try to find the first instance of that match.

In your case the first term is:

10 - 1 - 0159552

so this is the solution given.

Since your results are overlapping, you might want to check out this article.

Overlapping matches in Regex