Program:

The source code to convert a string from lowercase to uppercase in a given string is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//C# program to convert a string from 
//lowercase to uppercase.

using System;

class Demo
{
    public static void Main()
    {
        string text;
        Console.WriteLine("Enter a string:");
        
        text = Console.ReadLine();
        text = text.ToUpper();

        Console.WriteLine("String in Uppercase : "+text);
    }
}

Output:

Enter a string:
www.includehelp.com
String in Uppercase : WWW.INCLUDEHELP.COM
Press any key to continue . . .

Explanation:

Here, we created a Demo class that contains the Main() method. The Main() method is the entry point of the program. Here we read a string from the keyboard.

text = text.ToUpper();

Using the ToUpper() method, we converted the string from lowercase to uppercase and then printed the modified string on the console screen.