用于将用户名转换为Twitter等链接的正则表达式

Question

in twitter when you write @moustafa will change to <a href='user/moustafa'>@moustafa</a> now i want make the same thing when write @moustafa + space its change @moustafa only

Answer 1

One regular expression that could be used (shamelessly stolen from the @anywhere javascript library mentioned in another answer) would be:

\B\@([a-zA-Z0-9_]{1,20})

This looks for a non–word-boundary (to prevent a@b [i.e. emails] from matching) followed by @, then between one and 20 (inclusive) characters in that character class. Of course, the anything-except-space route, as in other answers; it depends very much on what values are to be (dis)allowed in the label part of the @label.

To use the highlighted regex in PHP, something like the following could be used to replace a string $subject.

$subject = 'Hello, @moustafa how are you today?';
echo preg_replace('/\B\@([a-zA-Z0-9_]{1,20})/', '<a href="user/$1">$0</a>', $subject);

The above outputs something like:

Hello, <a href="user/moustafa">@moustafa</a> how are you today?