calling_functions.cpp

// C# introduction examples:
// Calling a method without and with parameters and
// without and with return values.

using System;

namespace hello_world
{
    class Program
    {
        static void Main(string[] args)
        {

            // Call HelloWorld() method without input parameters and without a return value.
            HelloWorld();

            // Call Add() method with two input parameters (as literal values) and without a return value.
            Add(30, 40);

            // Call method Add() with two input parameters (as variable values) and without a return value.
            int no1 = 30;
            int no2 = 40;

            Add(no1, no2);

            // Call method Alert() and use default parameter value. The Alert() method does not return a value.
            Alert();

            // Call method Alert() with a custom parameter value. The Alert() method does not return a value.
            Alert("The program crashed!");

            // Call method Multiply() with two input parameters. Write the return value
            // to the console.
            int product = Multiply(20, 30);

            Console.WriteLine("Product: " + product.ToString());

        }

        static void HelloWorld()
        {
            
            // Write "Hello World!" to the console window.

            // This method does not accept any input parameters.
            // Also, it does not return a value.

            Console.WriteLine("Hello World!");

        }

        static void Add(int num1, int num2)
        {

            // Add two whole numbers and write the sum to the console window.
            
            // This method accepts two input parameters.
            // It does not return a value.

            int sum = num1 + num2;

            Console.WriteLine("Sum: " + sum.ToString());

        }

        static void Alert(string message = "Error!")
        {

            // Write the value of the input parameter message to the console window.
            // If the method is called without a parameter value, write the 
            // default value "Error!" Else, write the value that the parameter message
            // was set to when the method was called.

            // This method accepts one input parameter with a 
            // default value of "Error!".

            Console.WriteLine("Alert: " + message);

        }

        static int Multiply(int num1, int num2)
        {
            
            // Multiply two whole numbers provided as input parameters.
            // Return the product set in the variable called output.

            int output = num1 * num2;

            return output;

        }
    }
}