The Program in C# Program to find HCF (Highest Common Factor) of two numbers is given below:

using System;

namespace HCF
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello Codeauri Family, enter the first number here: ");
            int a = int.Parse(Console.ReadLine());

            Console.WriteLine("Similarly, enter the second number: ");
            int b = int.Parse(Console.ReadLine());

            int hcf = 1;
            int min = Math.Min(a, b);

            for (int i = 2; i <= min; i++)
            {
                if (a % i == 0 && b % i == 0)
                {
                    hcf = i;
                }
            }
            Console.WriteLine("Okay, The HCF of {0} and {1} is: {2}", a, b, hcf);
            Console.ReadLine();
        }
    }
}

Output:

Hello Codeauri Family, enter the first number here:
5
Similarly, enter the second number:
7
Okay, The HCF of 5 and 7 is: 1

Pro-Tips💡

Here are the step by step execution of above program:

1. The program begins by importing the “System” namespace, which provides access to various types and methods that are used in the program.
2. The code defines a namespace named “HCF”. The namespace is a way to organize and group related classes.
3. Within the namespace, the class named “Program” is defined. The Main method is defined inside this class and serves as the entry point for the program.
4. The Main method first asks the user to input the first number, which is stored in the integer variable named “a”.
5. The Main method then asks the user to input the second number, which is stored in the integer variable named “b”.
6. The Main method then declares an integer variable named “hcf” and initializes it to 1. This variable will store the HCF of the two numbers.
7. The Main method then finds the minimum of the two numbers “a” and “b” using the Math.Min method, and stores the result in the integer variable named “min”.
8. The Main method then uses a for loop to iterate from 2 to “min”.
9. Within the for loop, the Main method checks if the current iteration variable “i” is a factor of both “a” and “b” by checking if both “a % i == 0” and “b % i == 0”.
10. If “i” is a factor of both “a” and “b”, the Main method updates the value of “hcf” to “i”.
11. The Main method then prints the HCF of the two numbers to the console.
12. The Main method finally waits for the user to press the enter key, which allows the console window to remain open until the user closes it.