PHP preg_match for only numbers and letters, no special characters

Question

I don\'t want preg_match_all ... because the form field only allows for numbers and letters... just wondering what the right syntax is...

Nothing fancy ... just need to

Answer 1

If you just want to ensure a string contains only alphanumeric characters. A-Z, a-z, 0-9 you don't need to use regular expressions.

Use ctype_alnum()

Example from the documentation:

The above example will output:

The string AbCd1zyZ9 consists of all letters or digits.
The string foo!#$bar does not consist of all letters or digits.