How to Extract href Values from Tags Using Regular Expressions?

Use regular expressions to find the 'href' value of the <a> link

Extracting links from HTML can usually be done using a simple pattern such as "(?>.?)". However, this method falls short when trying to specifically get the 'href' attribute.

To solve this problem, we can use a more precise regular expression to locate the 'href' value within the <a> tag. Here is a valid pattern:

<code><a\s+(?:[^>]*?\s+)?href=(["'])(.*?)</code>

This regular expression works like this:

• Find the starting <a> tag.
• Optional matches any attribute or whitespace before the 'href' attribute.
• Capture the starting quote (single or double).
• Matches any characters between quotes and captures them as a group (this includes linked URLs).
• Make sure the closing quote matches the opening quote.

Using this regex you can extract the 'href' value from a link like this:

<code><a ....="" href="https://www.php.cn/link/3d7a8f67f51564c349478f7d52abee3b"></a>
<a ....="" href="http://https://www.php.cn/link/3d7a8f67f51564c349478f7d52abee3b"></a>
<a ....="" href="https://https://www.php.cn/link/3d7a8f67f51564c349478f7d52abee3b"></a></code>

However, it is important to note that this regex will also match links that do not contain the required "?" and "=" characters. If this is a problem, additional filtering may be required.

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