FBClient.Functions.CheckChars C# (CSharp) Method

        public static bool CheckChars(string str)
        {
            bool check = false;
            foreach (char chr in str)
            {
                foreach (char usable in USABLECHARS)
                {
                    if (chr.ToString().ToUpper() == usable.ToString().ToUpper())
                        check = true;
                }
                if (!check)
                {
                    return false;
                }
                else
                {
                    check = false;
                }
            }
            return true;
        }