loner_li 机试题 由用户输入一个字符串，使用foreach循环遍历出此字符串中有多个字母，多少个数字，多少个标点

 class Program
    {
        static void Main(string[] args)
        {
            //存放字母个数
            int countLetters = 0;
            //存放数字的个数
            int countDigits = 0;
            //存放标点符号的个数
            int countPunctuation = 0;
            //用户提供的输入
            string input;
            Console.WriteLine("请输入一个字符串");
            input = Console.ReadLine();
            //声明foreach循环以遍历输入的字符串中的每个字符
            foreach (char chr in input)
            {
                //检查字母
                if (char.IsLetter(chr))
                {
                    countLetters++;
                }
                //检查数字
                if (char.IsDigit(chr))
                {
                    countDigits++;
                }
                //检查标点
                if (char.IsPunctuation(chr))
                {
                    countPunctuation++;
                }

            }
            Console.WriteLine("字母的个数为：{0}",countLetters);
            Console.WriteLine("数字的个数为：{0}", countDigits);
            Console.WriteLine("标点符号的个数为：{0}", countPunctuation);

            Console.ReadKey();
         }
    }