Question

Having problems with this.

Let’s say I have a parameter composed of a single character and I only want to accept alphabetic characters. How will I determine that the parameter passed is a member of the latin alphabet (a–z)?

By the way Im using PHP Kohana 3.

Thanks.

Answer 1

Use the following guard clause at the top of your method:

if (!preg_match("/^[a-z]$/", $param)) {
    // throw an Exception...
}

If you want to allow upper case letters too, change the regular expression accordingly:

if (!preg_match("/^[a-zA-Z]$/", $param)) {
    // throw an Exception...
}

Another way to support case insensitivity is to use the /i case insensitivity modifier:

if (!preg_match("/^[a-z]$/i", $param)) {
    // throw an Exception...
}