查询字符串中字母出现的个数

/*查询字符串中字母出现的个数*/
            string str = " Welcom Hello World";
            Dictionary<char, int> dc = new Dictionary<char, int>();
            for (int i = 0; i < str.Length; i++) //遍历字符串的长度
            {
                if (str[i] == ' ')
                {
                    continue;
                }
                if (!dc.ContainsKey(str[i]))
                    {
                    dc.Add(str[i], 1);
                }
                else
                {
                    dc[str[i]]++;
                }
            }
            foreach (KeyValuePair<char,int> kv in dc)
            {
                Console.WriteLine("{0},{1}", kv.Key,kv.Value);
            }
            Console.ReadKey();