Csharp/C Sharp/Data Types/String Search

Search strings

<source lang="csharp"> /* C#: The Complete Reference by Herbert Schildt Publisher: Osborne/McGraw-Hill (March 8, 2002) ISBN: 0072134852

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// Search strings.

using System;

public class StringSearchDemo {

 public static void Main() { 
   string str = "C# has powerful string handling."; 
   int idx; 

   Console.WriteLine("str: " + str); 

   idx = str.IndexOf("h"); 
   Console.WriteLine("Index of first "h": " + idx); 

   idx = str.LastIndexOf("h"); 
   Console.WriteLine("Index of last "h": " + idx); 

   idx = str.IndexOf("ing"); 
   Console.WriteLine("Index of first \"ing\": " + idx); 

   idx = str.LastIndexOf("ing"); 
   Console.WriteLine("Index of last \"ing\": " + idx); 

   char[] chrs = { "a", "b", "c" }; 
   idx = str.IndexOfAny(chrs); 
   Console.WriteLine("Index of first "a", "b", or "c": " + idx); 

   if(str.StartsWith("C# has")) 
     Console.WriteLine("str begins with \"C# has\""); 

   if(str.EndsWith("ling.")) 
     Console.WriteLine("str ends with \"ling.\""); 
 } 

}

      </source>

String search Demo

<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765

• /

using System;
namespace StringSearch
{
    public class TesterStringSearch
    {
        public void Run()
        {
            // create some strings to work with
            string s1 = "One,Two,Three Liberty Associates, Inc. ";
            // constants for the space and comma characters
            const char Space = " ";
            const char Comma = ",";
            // array of delimiters to split the sentence with
            char[] delimiters = new char[]
            {
                Space,
                Comma
            };
            string output = "";
            int ctr = 1;
            // split the string and then iterate over the
            // resulting array of strings
            String[] resultArray = s1.Split(delimiters);
            foreach (String subString in resultArray)
            {
                output += ctr++;
                output += ": ";
                output += subString;
                output += "\n";
            }
            Console.WriteLine(output);
        }
        static void Main()
        {
            TesterStringSearch t = new TesterStringSearch();
            t.Run();
        }
    }
}
          
      </source>

String search: last index

<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765

• /

using System;
namespace StringSearch
{
   public class TesterStringLastIndex
   {
      public void Run()
      {
          // create some strings to work with
          string s1 = "One Two Three Four";
          int index;
          // get the index of the last space
          index=s1.LastIndexOf(" ");
          // get the last word.
          string s2 = s1.Substring(index+1);
          // set s1 to the substring starting at 0
          // and ending at index (the start of the last word
          // thus s1 has one two three
          s1 = s1.Substring(0,index);
          // find the last space in s1 (after two)
          index = s1.LastIndexOf(" ");
          // set s3 to the substring starting at
          // index, the space after "two" plus one more
          // thus s3 = "three"
          string s3 = s1.Substring(index+1);
          // reset s1 to the substring starting at 0
          // and ending at index, thus the string "one two"
          s1 = s1.Substring(0,index);
          // reset index to the space between
          // "one" and "two"
          index = s1.LastIndexOf(" ");
          // set s4 to the substring starting one
          // space after index, thus the substring "two"
          string s4 = s1.Substring(index+1);
          // reset s1 to the substring starting at 0
          // and ending at index, thus "one"
          s1 = s1.Substring(0,index);
          // set index to the last space, but there is
          // none so index now = -1
          index = s1.LastIndexOf(" ");
          // set s5 to the substring at one past
          // the last space. there was no last space
          // so this sets s5 to the substring starting
          // at zero
          string s5 = s1.Substring(index+1);
          Console.WriteLine ("s2: {0}\ns3: {1}",s2,s3);
          Console.WriteLine ("s4: {0}\ns5: {1}\n",s4,s5);
          Console.WriteLine ("s1: {0}\n",s1);
      }
      static void Main()
      {
         TesterStringLastIndex t = new TesterStringLastIndex();
         t.Run();
      }
   }
}
          
      </source>

String split and search

<source lang="csharp"> /* Learning C# by Jesse Liberty Publisher: O"Reilly ISBN: 0596003765

• /

using System;
using System.Text;
namespace StringSearch
{
   public class TesterStringSearch1
   {
      public void Run()
      {
          // create some strings to work with
          string s1 = "One,Two,Three Liberty Associates, Inc.";
          // constants for the space and comma characters
          const char Space = " ";
          const char Comma = ",";
          // array of delimiters to split the sentence with
          char[] delimiters = new char[]
         {
             Space,
             Comma
         };
          // use a StringBuilder class to build the
          // output string
          StringBuilder output = new StringBuilder();
          int ctr = 1;
          // split the string and then iterate over the
          // resulting array of strings
          foreach (string subString in s1.Split(delimiters))
          {
              // AppendFormat appends a formatted string
              output.AppendFormat("{0}: {1}\n",ctr++,subString);
          }
          Console.WriteLine(output);
      }
      [STAThread]
      static void Main()
      {
         TesterStringSearch1 t = new TesterStringSearch1();
         t.Run();
      }
   }
}

      </source>

use the IndexOf() and LastIndexOf() methods to search for substrings and characters;

<source lang="csharp">

using System; class MainClass {

   public static void Main() {
       string[] myStrings = {"To", "be", "or", "not","to", "be"};
       string myString = String.Join(".", myStrings);        
       int index = myString.IndexOf("be");
       Console.WriteLine("\"be\" first occurs at index " + index + " of myString");
       index = myString.LastIndexOf("be");
       Console.WriteLine("\"be\" last occurs at index " + index + " of myString");
       index = myString.IndexOf("b");
       Console.WriteLine(""b" first occurs at index " + index + " of myString");
       index = myString.LastIndexOf("b");
       Console.WriteLine(""b" last occurs at index " + index + " of myString");

   }

}

</source>