php中的正则表达式，用给定的模式搜索url

Question

I want to search a given text for local URLs in link's href attributes, using regular expression. Currently, I have this regular expression:

'/href=["\']?([^"\'>]+)["\']?/'

Now, I'd like to add some more filtering: Only get those links, which start like this:

XXXX-XX-XX

Where X is a number. This should match this: 2015-05-15/, 2015-05-15_03_21_32/ and also 2014-12-21 (any date set by me).

Answer 1

You can use the following regex:

href=["']?(\d{4}(?:[-_]\d{2})+)["']?

PHP: $re = "#href=[\"']?(\d{4}(?:[-_]\d{2})+)[\"']?#";

Explanation:

• href=["']? - matches href= and an optional single or double quote
• (\d{4}(?:[-_]\d{2})+) - a capturing group around the href attribute value
  • \d{4} - Exactly 4 digits
  • (?:[-_]\d{2})+ - 1 or more groups of -/_ + 2-digit numbers
• ["']? - matches an optional single or double quote

See Regex demo here and IDEONE demo