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 −

 Live Demo

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("
String 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 −

 Live Demo

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("
String 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!

Updated on: 04-Dec-2019

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