C# Retrieve case-insensitive and highlight instance details

C# Retrieve case-insensitive and highlight instance details

Today, I encountered a problem: how to highlight case-insensitive keywords in web pages

For example: the text abcaBcabCaBCabcaBCa, the keyword bc, has a total of 6 matches in case insensitive situations.

Then the abcaBcabCaBCabcaBCa is displayed on the web page.

Many people think of it as a replace function. However, the replace function in c# cannot solve the problem of letter case.

For example, bc, Bc, bC, and BC have all been searched, but cannot be replaced with a text in a uniform manner

The above text is reproduced from the article "Wancang Yishu" by Daniu--"Highlighting the case-insensitive keyword - ASP".

But his article is written in the ASP version, and today I write in the C# version; let’s talk about the solution below.

Solution: Use IndexOf

IndexOf(String, Int32, StringComparison)

The index of the specified string's first match in the current String object.

parameter

value
type： System. String 
String to search。
startIndex
type： System. Int32 
Search for the starting location。
comparisonType
type： System. StringComparison 
Specify one of the enumeration values for the search rule。
（OrdinalIgnoreCase：Use sequence number collation and ignore case of string being compared，Comparison of strings。）

Code

/// &lt;summary&gt;
    /// Highlight to find keywords.    /// &lt;/summary&gt;
    /// <param name="str">text.  </param>    /// <param name="keyword">Keyword</param>    /// <returns> Text with highlighted logo.  </returns>    /// &lt;remarks&gt;
    /// 1. Letters are case-insensitive.    /// 2. The name of CssClass is highlight.    /// &lt;/remarks&gt;
    private string HighLightKeyword(string str, string keyword)
    {
      int index;
      var startIndex = 0;
      const string highLightBegin = "&lt;span class='highlight'&gt;";
      const string highLightEnd = "&lt;/span&gt;";
      var length =  + ;
      var lengthHighlight = length + ;

      while ((index = (keyword, startIndex, )) &gt; -1)
      {
        str = (index, highLightBegin).Insert(index + length, highLightEnd);
        startIndex = index + lengthHighlight;
      }

      return str;
    }

Thank you for reading, I hope it can help you. Thank you for your support for this site!