string s1 = "HELLO WORLD";
string s2 = "hello world";
Console.WriteLine("———————————————————————————————————————————");
Console.WriteLine("Program to perform the string operations");
Console.WriteLine("———————————————————————————————————————————");
Console.WriteLine("Length of string is " + s1.Length);
string r = new string(s1.ToCharArray().Reverse().ToArray());
Console.WriteLine("\nReverse string is " + r);
Console.WriteLine("\nUppercase string is " + s2.ToUpper());
Console.WriteLine("\nLowercase string is " + s1.ToLower());
if (s1.CompareTo(s2) == 0)
{
    Console.WriteLine("\nStrings are equal");
}
else
{
    Console.WriteLine("\nStrings are not equal");
}
if (s1 == r)
{
    Console.WriteLine("\n{0} String is palindrome", s1);
}
else
{
    Console.WriteLine("\n{0} String is not palindrome", s1);
}
Console.WriteLine("\nSubstring - " + s1.Substring(7));
Console.WriteLine("\nString replaced - " + s1.Replace("WORLD", "Programmers"));
Console.WriteLine("\nIndexOf string - " + s1.IndexOf("W"));
Console.WriteLine("———————————————————————————————————————————");

kodingwindow@kw:~/csharp$ dotnet run
———————————————————————————————————————————
Program to perform the string operations
———————————————————————————————————————————
Length of string is 11

Reverse string is DLROW OLLEH

Uppercase string is HELLO WORLD

Lowercase string is hello world

Strings are not equal

HELLO WORLD String is not palindrome

Substring - ORLD

String replaced - HELLO Programmers

IndexOf string - 6
———————————————————————————————————————————
kodingwindow@kw:~/csharp$