Detecting special characters PHP

Question

I am trying to check whether a string contains any special chars so I know what to do with it afterwards in my script.

Heres what I have:

if (preg_match(         


        

Answer 1

You could compare all alphanumeric characters against the string to check if there is any special character:

$temp = '$tack0verflow_';

if(strlen($temp) == strlen(preg_replace("/[^a-zA-Z0-9]+/", "", $temp))){
    // No special characters
} else {
    // Has special characters
}