Home » .Net » C# Programs

Demonstrate the example of IndexOf() method of string class in C#

String.IndexOf() method in C#: Here, we will learn with an example, how to find index of a substring in a string? Its returns index of first character exists in the string.

Given a string and we have find the index of a substring.

String.IndexOf() method

It is a method of string class, which returns the first index (first occurrence) of the character in a string.

Syntax:

int String.IndexOf(String str);

This method returns integer value; it returns the index when sub-string found in string. If sub-string is not found in string then it returns negative value.

Example of String.IndexOf() in C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main()
        {
            String str1;
            String str2;

            Console.Write("Enter string : ");
            str1 = Console.ReadLine();

            Console.Write("Enter sub string : ");
            str2 = Console.ReadLine();

            int index = str1.IndexOf(str2);

            if (index < 0)
                Console.WriteLine("Sub string is not find in string");
            else
                Console.WriteLine("Index str2 in str1 is: "+index);
        }
    }
  
}

Output

Enter string : Hello, How are you?
Enter sub string : How
Index str2 in str1 is: 7

C# Basic Programs »

---