CSharp - String String Searching

Introduction

You can search within strings with StartsWith, EndsWith and Contains methods.

These all return true or false:

Demo

using System;
class MainClass{//  ww  w . ja v  a 2  s.  c om
   public static void Main(string[] args)
   {
     Console.WriteLine ("this is a test".EndsWith ("test"));      
     Console.WriteLine ("this is a test".Contains ("is"));    
   }
}

Result

StartsWith and EndsWith can accept StringComparison enum or a CultureInfo object to control case and culture sensitivity.

The default is to perform a case-sensitive match using rules applicable to the current culture.

The following code performs a case-insensitive search using the invariant culture's rules:

Demo

using System;
class MainClass//from  w w w.j av  a 2  s  .c  o m
{
   public static void Main(string[] args)
   {
       bool b = "abcdef".StartsWith ("aBc", StringComparison.InvariantCultureIgnoreCase);
       Console.WriteLine(b);

   }
}

Result

IndexOf returns the first position of a given character or substring or -1 if the substring isn't found:

Demo

using System;
class MainClass{/*from  w w w. j  a v a  2 s .c o m*/
   public static void Main(string[] args){
       Console.WriteLine ("abcde".IndexOf ("cd"));   // 2
   }
}

Result

IndexOf is overloaded to accept a startPosition which is an index from which to begin searching, as well as a StringComparison enum:

Console.WriteLine ("abcde abcde".IndexOf ("CD", 6,
               StringComparison.CurrentCultureIgnoreCase));    // 8

LastIndexOf works backward through the string.

IndexOfAny returns the first matching position of any one of a set of characters:

Demo

using System;
class MainClass/*  w  ww .j  a va 2  s. c o m*/
{
   public static void Main(string[] args)
   {
     Console.Write ("ab,cd ef".IndexOfAny (new char[] {' ', ','} ));       // 2
     Console.Write ("pas5w0rd".IndexOfAny ("0123456789".ToCharArray() ));  // 3

   }
}

Result

LastIndexOfAny does the same in the reverse direction.

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