PHP字符串分割，首字母大写

/**
     * 写一个方法可以实现如下功能；
        server_name转为 serverName
        user_name 转为 userName
        pass_word_id 转为 passWordId
     */

    function getStr($str){
        if(empty($str)) return false;
        $arr = explode('_',$str);
        $newArr = [];
        foreach($arr as $key => $value){
            if($key > 0){
                $newArr[] = ucfirst($value);
            }else{
                $newArr[] = $value;
            }
        }
        $newStr = implode('',$newArr);
        return $newStr;
    }
    $str = "array_chunk_ee";
    $string = getStr($str);
    print_r($string);