C# String.IndexOf( ) Method

The String.IndexOf() method in C# is used to find the zero-based index of the first occurrence of a specified Unicode character or string within this instance.

Syntax

The syntax is as follows −

public int IndexOf (string val);

Above, val is the string to find.

Example

Let us now see an example −

using System;
public class Demo {
   public static void Main(String[] args) {
      string str1 = "Jacob";
      string str2 = "John";
      Console.WriteLine("String 1 = "+str1);
      Console.WriteLine("HashCode of String 1 = "+str1.GetHashCode());
      Console.WriteLine("Index of character 'o' is str1 = " + str1.IndexOf("o"));
      Console.WriteLine("\nString 2 = "+str2);
      Console.WriteLine("HashCode of String 2 = "+str2.GetHashCode());
      Console.WriteLine("Index of character 'o' is str2 =" + str2.IndexOf("o"));
      bool res = str1.Contains(str2);
      if (res)
         Console.WriteLine("Found!");
      else
         Console.WriteLine("Not found!");
   }
}

Output

This will produce the following output −

String 1 = Jacob
HashCode of String 1 = -790718923
Index of character 'o' is str1 = 3
String 2 = John
HashCode of String 2 = -1505962600
Index of character 'o' is str2 =1
Not found!

Example

Let us now see another example −

using System;
public class Demo {
   public static void Main(String[] args) {
      string str1 = "Kevin";
      string str2 = "Evin";
      Console.WriteLine("String 1 = "+str1);
      Console.WriteLine("HashCode of String 1 = "+str1.GetHashCode());
      Console.WriteLine("Index of character 'k' in str1 = " + str1.IndexOf("k"));
      Console.WriteLine("\nString 2 = "+str2);
      Console.WriteLine("HashCode of String 2 = "+str2.GetHashCode());
      Console.WriteLine("Index of character 'k' in str2 =" + str2.IndexOf("k"));
      bool res = str1.Contains(str2);
      if (res)
         Console.WriteLine("Found!");
      else
         Console.WriteLine("Not found!");
   }
}

Output

This will produce the following output −

String 1 = Kevin
HashCode of String 1 = -768104063
Index of character 'k' in str1 = -1
String 2 = Evin
HashCode of String 2 = 1223510568
Index of character 'k' in str2 =-1
Not found!