156-练习9和10 循环练习和字符串与字符的处理

9,财务处的小云老师最近就在考虑一个问题：如果每个老师的工资额都知道，最少需要准备多少张人民币，才能在给每位老师发工资的时候都不用老师找零呢？
这里假设老师的工资都是正整数，单位元，人民币一共有100元、50元、10元、5元、2元和1元六种。

            int num = Convert.ToInt32(Console.ReadLine());
            int count100 = num / 100;
            int remain = num % 100;
            int count50 = remain / 50;
            remain = remain % 50;
            int count10 = remain / 10;
            remain = remain % 10;
            int count5 = remain / 5;
            remain = remain % 5;
            int count2 = remain / 2;
            remain = remain % 2;
            Console.WriteLine("100的准备" + count100);
            Console.WriteLine("50的准备" + count50);
            Console.WriteLine("10的准备" + count10);
            Console.WriteLine("5的准备" + count5);
            Console.WriteLine("2的准备" + count2);
            Console.WriteLine("1的准备" + remain);

10，输入一个字符串，判断其是否是C#的合法标识符。

            string str = Console.ReadLine();
            bool isRight = true;
            if ((str[0] >= 'a' && str[0] <= 'z') || (str[0] >= 'A' && str[0] <= 'Z') || str[0] == '_' || str[0] == '@')
            {

            }
            else
            {
                isRight = false;
            }
            for (int i = 1; i < str.Length; i++)
            {
                if ((str[i] >= 'a' && str[i] <= 'z') || (str[i] >= 'A' && str[i] <= 'Z') || str[i] == '_' || (str[i] >= '0' && str[i] <= '9'))
                {

                }
                else
                {
                    isRight = false;
                }
            }
            if (isRight == false)
            {
                Console.WriteLine("不是合法标识符");
            }
            else
            {
                Console.WriteLine("是合法标识符");
            }
            Console.ReadKey();