Calculator Example For C# Beginners

Calculator.cs

using System;
using System.Linq;

namespace Example
{
	class Program
	{
		static string[] Operators = { "+", "-", "*", "/" };

		static void Main()
		{
			Console.WriteLine("Calculator");
			Console.WriteLine($"Supported Operations: {string.Join(", ", Operators)}");
			Console.WriteLine();

			int a = GetInt();
			int b = GetInt(prompt: "Please Enter Another Number: ");
			string operation = GetOperation();

			int result = operation switch
			{
				"+" => a + b,
				"-" => a - b,
				"*" => a * b,
				"/" => a / b,
				_ => throw new NotImplementedException(),
			};
			Console.WriteLine($"Result ({a} {operation} {b}): {result}");

			Console.WriteLine();
			Console.WriteLine("Press Enter To Continue...");
			Console.ReadLine();
		}

		public static int GetInt(string prompt = null)
		{
			prompt ??= "Please Enter Number: ";
			Console.Write(prompt);
			var input = Console.ReadLine();
			int inputValue;
			bool success = int.TryParse(input, out inputValue);
			while (!success)
			{
				Console.WriteLine("Invalid Input. Try Again...");
				Console.Write(prompt);
				input = Console.ReadLine();
				success = int.TryParse(input, out inputValue);
			}
			return inputValue;
		}

		public static string GetOperation(string prompt = null)
		{
			prompt ??= $"Please Enter Operation({string.Join(", ", Operators)}): ";
			Console.Write(prompt);
			var input = Console.ReadLine();
			bool success = Operators.Contains(input);
			while (!success)
			{
				Console.WriteLine("Invalid Input. Try Again...");
				Console.Write(prompt);
				input = Console.ReadLine();
				success = Operators.Contains(input);
			}
			return input;
		}
	}
}