PHP function that determines if a string starts with an upper-case letter A-Z

php-upper-case-checker.php

<?php

/**
* This class contains sting helper functions.
*
* @package    StringHelper
* @author     Williams Isaac
* @version    1.0
*/

class StringHelper {
    
    private $string_val = null;
    private $on_position = null;
    
    function __construct() {
        
    }
    
    /**
    * Setter function to ser falues.
    *
    * @name    caseChecker
    * @var     string $string String to check for
    * @var     string $position Position to check for, default 0
    */
    
    public function caseChecker($string, $position = 0) { 
        if(!$this->testIsString($string)){
            throw new Exception("This value: ".$string." is not a valid string");
        }else{
            $this->string_val = $string;
            $this->on_position = $position;
            return $this;
        }
    }
    
    /**
    * Test if the string is valid.
    *
    * @name    testIsString
    * @var     string $string String to check for
    */
    
    private function testIsString($string){
        return is_string($string);
    }
    
    /**
    * Test if string contains special characters 
    *
    * @name    containsSpecialChars
    */
    
    public function containsSpecialChars(){
        if(!ctype_alnum(str_replace(array('-', '_'), '', $this->string_val))){
            throw new Exception("This value: ".$this->string_val." cannot contain special characters");
        }else{
            return $this;
        }
    }
    
    public function val(){
        return ctype_upper($this->string_val[$this->on_position]);
    }
    
}

(new StringHelper)->caseChecker("Shh%d")->containsSpecialChars()->val(); //Exception: This value: Shh%d cannot contain special characters

(new StringHelper)->caseChecker("Shhd")->val(); // true

(new StringHelper)->caseChecker("shhd")->val(); // false

(new StringHelper)->caseChecker(4492)->containsSpecialChars()->val(); //Exception: This value: 4492 is not a valid string
?>