獲取輸入字符串的位置，然後得到兩端的子字符串

我有一個搜索功能，可以搜索文本塊中的關鍵字並顯示結果的截斷版本。我的問題是它不會顯示搜索關鍵字，如果它接近尾聲。獲取輸入字符串的位置，然後得到兩端的子字符串

例如。「

Text =」文本塊是以某種方式分組在一起的文本，例如在網頁上使用段落或塊引用。文本常常呈現方形或矩形塊的形狀「

我搜索‘時代’與

text = text.Substring(0, 100) + "...";

它將返回

"A block of text is text that is grouped together in some way, such as with the use of paragraphs or..."

有沒有一種方法所搜索的關鍵詞之前和之後返回100個字符？

來源

2017-07-19 KevinC

設置最後100個字符：'text.Substring（text.Length - 100，100）'。 'text.Substring（0，100）'對於返回前100個是正確的。 –

這將適用於某些情況。然而，如果文本塊的長度爲500個字符，而搜索的關鍵字在位置100的中間呢？這在這種情況下不起作用。 – KevinC

如果你不想截斷單詞，即使單詞超過了100個字符的限制，我建議你用空格和關鍵字搜索一起使用'StringBuilder'＆'Split'：http://joelabrahamsson.com/c-method-for -cropping文本，不破字/。 –

 string s = "A block of text is text that is grouped together in some way, such as with the use of paragraphs or"; 
     string wordtoSearch = "block"; 
     int firstfound = s.IndexOf(wordtoSearch); 

     // If the index of the first letter found is greater than 100, get the 100 letters before the found word and 100 letters after the found word 
     if (firstfound > 100) 
     { 
      string before = s.Substring(firstfound , firstfound-100); 
      string after = s.Substring(firstfound + wordtoSearch.Length, 100); 
      Console.WriteLine(before); 
      Console.WriteLine(after); 
     } 
    //// If the index of the first letter found is less than 100, get the letters before the found word and 100 letters after the found word 
     if(firstfound < 100) 
     { 
      string before = s.Substring(0, firstfound); 
      Console.WriteLine(before); 
      if(s.Length >100) 
      { 
      string after = s.Substring(firstfound + wordtoSearch.Length, 100); 
      Console.WriteLine(after); 
      } 
      else 
      { 
       string after = s.Substring(firstfound + wordtoSearch.Length); 
       Console.WriteLine(after); 
      } 
     }

來源

2017-07-19 02:53:36 SailajaPalakodeti

感謝這似乎爲我工作。我修改了代碼abit ----- before = s.Substring（firstfound - 99，firstfound - （firstfound - 99））; – KevinC

你可以做到這一點，

string s = "A block of text is text that is grouped together in some way, such as with the use of paragraphs or"; 
    string toBeSearched = "grouped"; 
    int firstfound = s.IndexOf(toBeSearched);  
    if (firstfound != -1) 
    { 
     string before = s.Substring(0 , firstfound); 
     string after = s.Substring(firstfound + toBeSearched.Length);   
    }

DEMO

來源

2017-07-19 02:24:56 Sajeetharan

爲了使它稍微泛化，用'Math.Max（0，firstfound - 100）替換'0' –

你可以做這樣的事情爲好，使之更有點重複使用，能夠匹配關鍵字的多個實例

string input = "A block of text is text that is grouped together in some way, such as with the use of paragraphs or blockquotes on a Web page. Often times, the text takes on the shape of a square or rectangular block"; 
int buffer = 30; // how much do you want to show before/after 
string match = "times"; 

int location = input.IndexOf(match); 
while (location != -1) { 
    // take buffer before and after: 
    int start = location - Math.Min (buffer , location); // don't take before start 
    int end = location + match.Length 
      + Math.Min(buffer, input.Length - location - match.Length); // don't take after end 
    Console.WriteLine("..." + input.Substring(start, end-start) + "..."); 
    location = input.IndexOf(match,location+1); 
}

給你輸出

...A block of text is text that is gro... 
...with the use of paragraphs or blockquotes on a Web page. Often ... 
...pe of a square or rectangular block...

來源

2017-07-19 02:45:31 Noctis

獲取輸入字符串的位置，然後得到兩端的子字符串

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