《深入理解C#》代码片段-用Dictionary<TKey,TValue>统计文本中的单词

 1     public class Words
 2     {
 3         public static Dictionary<string, int> CountWords(string text)
 4         {
 5             Dictionary<string, int> frequencies;//创建从单词到频率的新映射
 6             frequencies = new Dictionary<string, int>();
 7             string[] words = Regex.Split(text, @"\W+");//将文本分解成单词
 8             //添加或跟新映射
 9             foreach (var word in words)
10             {
11                 if (frequencies.ContainsKey(word))
12                 {
13                     frequencies[word]++;
14                 }
15                 else
16                 {
17                     frequencies[word] = 1;
18                 }
19             }
20             return frequencies;
21         }
22     }

 1   static void Main(string[] args)
 2   {
 3       string text = "President Xi Jinping has asked the armed forces to clear up the bad influence left by the graft case of Xu Caihou, a former senior commander.";
 4       Dictionary<string, int> frequencies = Words.CountWords(text);
 5       foreach (KeyValuePair<string,int> entry in frequencies)
 6       {
 7           string word = entry.Key;
 8           int frequency = entry.Value;
 9           Console.WriteLine("{0}:{1}", word, frequency);
10       }
11       Console.ReadKey();
12   }