PHP preg_replace_callback not replacing my "matches"

Question

Why is this returning the original string and not the edited string?

Original String:

I cant believe Ed ate [-food-] for breakfast.

Replace:

preg_replace_callback('/\[\-[a-zA-Z0-9_]\-\]/', 'tag_func', $email_body);

function tag_func($matches){
     $matches[0] = 'tacos';
     return $matches[0];
}

Outcome Desired String:

I cant believe Ed ate tacos for breakfast.

This is my warning I'm getting:

preg_replace_callback(): Requires argument 2, 'tag_func', to be a valid callback 

Answer 1

You forgot to add a +, so that it should match multiple characters:

preg_replace_callback('/\[-[a-z\d_]+-\]/i', 'tag_func', $email_body);
//                                 ^

See it here in action: http://codepad.viper-7.com/f94VPy

---

If you're running 5.3, you can pass it an anonymous function directly:

preg_replace_callback('/\[-[a-z\d_]+-\]/i', function () {
    return 'tacos';
}, $email_body);

Here's the demo: http://codepad.viper-7.com/NGBAIh