计算字符串中整个单词的出现次数

Question

我想查找字符串中特定单词的出现次数。

我在网上搜索过，发现很多答案，比如

• Stack Overflow Answer
• Answer from DotNetPerl

但他们都没有给我准确的结果。

我想要的是：

输入：

I have asked the question in StackOverflow. Therefore i can expect answer here.

“The”关键字的输出：

The keyword count: 2

注意：不应该在句子中考虑“因此”中的“The”。

基本上我想匹配整个单词并得到计数。

Answer 1

试试这个

var searchText=" the ";
var input="I have asked the question in StackOverflow. Therefore i can expect answer here.";
var arr=input.Split(new char[]{' ','.'});
var count=Array.FindAll(arr, s => s.Equals(searchText.Trim())).Length;
Console.WriteLine(count);

DOTNETFIDDLE

修改

为您的搜索句子

var sentence ="I have asked the question in StackOverflow. Therefore i can expect answer here.";
var searchText="have asked";
char [] split=new char[]{',',' ','.'};
var splitSentence=sentence.ToLower().Split(split);
var splitText=searchText.ToLower().Split(split);
Console.WriteLine("Search Sentence {0}",splitSentence.Length);
Console.WriteLine("Search Text {0}",splitText.Length);
var count=0;
for(var i=0;i<splitSentence.Length;i++){
    if(splitSentence[i]==splitText[0]){
      var index=i;
        var found=true;
        var j=0;
        for( j=0;j<splitText.Length;j++){
          if(splitSentence[index++]!=splitText[j])
          {
              found=false;
              break;
          }
        }
        if(found){
            Console.WriteLine("Index J {0} ",j);
            count++;
            i= index >i ? index-1 : i;
        }
    }

}
Console.WriteLine("Total found {0} substring",count);

DOTNETFIDDLE

Answer 2

可能的解决方案是使用Regex：

var count = Regex.Matches(input.ToLower(), String.Format("\b{0}\b", "the")).Count;

Answer 3

尝试这样（方法1）

string SpecificWord = " the ";
            string sentence = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
            int count = 0;
            foreach (Match match in Regex.Matches(sentence, SpecificWord, RegexOptions.IgnoreCase))
            {
                count++;
            }
            Console.WriteLine("{0}" + " Found " + "{1}" + " Times", SpecificWord, count);

或这样（方法2）

string SpecificWord = " the ";
string sentence = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
int WordPlace = sentence.IndexOf(SpecificWord);
Console.WriteLine(sentence);
int TimesRep;
for (TimesRep = 0; WordPlace > -1; TimesRep++)
{
    sentence = (sentence.Substring(0, WordPlace) +sentence.Substring(WordPlace +SpecificWord.Length)).Replace("  ", " ");
    WordPlace = sentence.IndexOf(SpecificWord);
}

Console.WriteLine("this word Found " + TimesRep + " time");

Answer 4

您可以使用while循环搜索第一次出现的索引，然后从找到的索引++位置进行搜索并在循环结束时设置一个计数器。循环变为直到索引== -1。

Answer 5

试试这个

string Text = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
                Text = Text.ToLower();
                Dictionary<string, int> frequencies = null;
                frequencies = new Dictionary<string, int>();
                string[] words = Regex.Split(Text, "\\W+");
                foreach (string word in words)
                {
                    if (frequencies.ContainsKey(word))
                    {
                        frequencies[word] += 1;
                    }
                    else
                    {
                        frequencies[word] = 1;
                    }
                }


                foreach (KeyValuePair<string, int> entry in frequencies)
                {
                    string word = entry.Key;
                    int frequency = entry.Value;
                    Response.Write(word.ToString() + "," + frequency.ToString()+"</br>");
                }

要搜索特定字，请尝试使用Like This。

string Text = "I have asked the question in StackOverflow. Therefore the i can expect answer here.";
        Text = Text.ToLower();
        string searchtext = "the";
        searchtext = searchtext.ToLower();
        string[] words = Regex.Split(Text, "\\W+");
        foreach (string word in words)
        {
            if (searchtext.Equals(word))
            {
                count = count + 1;
            }
            else
            {
            }
        }
        Response.Write(count);

Answer 6

问题不是你想的那么简单;应该注意许多问题，例如标点符号，字母大小写以及如何识别字边界等问题。 但是，使用N_Gram概念，我提供了以下解决方案：

1-确定密钥中有多少个单词。将其命名为N

2-提取文本中所有N个连续的单词序列（N_Grams）。

3-计算N_Grams

中键的出现次数

    string text = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
    string key = "the question";
    int gram = key.Split(' ').Count();
    var parts = text.Split(' ');
    List<string> n_grams = new List<string>();
    for (int i = 0; i < parts.Count(); i++)
    {
        if (i <= parts.Count() - gram)
        {
            string sequence = "";
            for (int j = 0; j < gram; j++)
            {
                sequence += parts[i + j] + " ";
            }
            if (sequence.Length > 0)
                sequence = sequence.Remove(sequenc.Count() - 1, 1);
            n_grams.Add(sequence);
        }
    }

    // The result
    int count = n_grams.Count(p => p == key);

}

例如，对于密钥= the question并将single space视为字边界，会提取以下二维字符：

我有 已经问过了 问 问题
问题 在StackOverflow中。
堆栈溢出。因此
因此我 我可以 可以期待的 期待答案
回答这里。

以及the question在文本中出现的次数并不明显：1

Answer 7

此解决方案应在字符串所在的任何位置使用：

var str = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
var numMatches = Regex.Matches(str.ToUpper(), "THE")
    .Cast<Match>()
    .Count(match => 
        (match.Index == 0 || str[match.Index - 1] == ' ') && 
        (match.Index + match.Length == str.Length || 
            !Regex.IsMatch(
                str[match.Index + match.Length].ToString(),
                "[a-zA-Z]")));

.NET Fiddle

Answer 8

string input = "I have asked the question in StackOverflow. Therefore i can expect answer here.";
string pattern = @"\bthe\b";
var matches = Regex.Matches(input, pattern, RegexOptions.IgnoreCase);
Console.WriteLine(matches.Count);

请参阅正则表达式Anchors - “\ b”。

Answer 9

对整个字符串中的整个单词进行计数有很多可能性。
例如

第一

string name = "pappu kumar sdffnsd sdfnsdkfbsdf sdfjnsd fsdjkn fsdfsd sdfsd pappu kumar";
var res= name.Contains("pappu kumar");
var splitval = name.Split("pappu kumar").Length-1;

第二：

var r = Regex.Matches(name, "pappu kumar").Count;

Answer 10

那又怎么样（似乎比其他解决方案更有效）：

public static int CountOccurences(string haystack, string needle)
{
    return (haystack.Length - haystack.Replace(needle, string.Empty).Length) / needle.Length;
}

Answer 11

也尝试将其用于结构化数据。

    var splitStr = inputStr.Split(' ');
    int result_count = splitStr.Count(str => str.Contains("userName"));