统计字符串中单词出现的次数

Question

我在 .Net C# 中有这个项目，我必须在其中计算字符串中单词出现的次数。我得到一个 KeyNotFoundException，在我递增变量以显示单词重复次数的地方。代码如下：向下滚动错误

public static Dictionary<string, int> Process(string phrase)
{
    Dictionary<string, int> wordsAndCount = new Dictionary<string, int>();

    string[] words = phrase.Replace("\"", "").Replace("'", "").Replace(".", "").Replace(",", "").Replace("\n", "").Split(' ');
    for (int index = 0; index <= words.Length; index++)
    {
        string word = words[index];
        wordsAndCount[word] = wordsAndCount[word] + 1;
    }
    Dictionary<string, int> dictionary = new Dictionary<string, int>();

    foreach (KeyValuePair<string, int> pair in wordsAndCount.OrderByDescending((s) => s.Key))
        dictionary.Add(pair.Key, pair.Value);

    wordsAndCount = dictionary;
    return wordsAndCount;
}

}

错误

wordsAndCount[word] = wordsAndCount[word] + 1; KeyNotFoundException was unhandled
An unhandled exception of type 'System.Collections.Generic.KeyNotFoundException' occurred in mscorlib.dll

Answer 1

您的循环包含两个问题：

如果密钥不存在则不能使用（使用 ContainsKey 测试）

你应该循环直到索引 < words.Length

for (int index = 0; index < words.Length; index++)
{
    string word = words[index];
    if(!wordsAndCount.ContainsKey(word))
        wordsAndCount.Add(word, 1);
    else
        wordsAndCount[word]++;
}

您还可以 trim 使用这种方法对您的字典进行排序，减少一些代码

var temp = wordsAndCount.OrderByDescending (ac => ac.Key);
return temp.ToDictionary (t => t.Key, t => t.Value);

Answer 2

试试这个：

字符串B在字符串A中出现的次数

var NumberOfOccurrences = A.Split(new string[] { B }, StringSplitOptions.None).Length - 1;

统计字符串中单词出现的次数

Count number of word occurrences in a string

c#

string

count

words