PHP - detect whitespace between strings

Question

How would I go about detecting whitespace within a string? For example, I have a name string like:

\"Jane Doe\"

Keep in mind that I don\'t want to trim or re

Answer 1

// returns no. of matches if $str has nothing but alphabets,digits and spaces. function 

    is_alnumspace($str) {
          return preg_match('/^[A-Za-z0-9 ]+$/i',$str);
    }

// This variation allows uppercase and lowercase letters.