Initialize C# project for .NET 9.0 with basic calculator functionality

Csharp/Calc/Program.cs

@@ -0,0 +1,47 @@
+using System;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+        Console.WriteLine("Enter the first number:");
+        double num1 = Convert.ToDouble(Console.ReadLine());
+
+        Console.WriteLine("Enter an operator (+, -, *, /):");
+        string op = Console.ReadLine();
+
+        Console.WriteLine("Enter the second number:");
+        double num2 = Convert.ToDouble(Console.ReadLine());
+
+        double result = 0;
+
+        switch (op)
+        {
+            case "+":
+                result = num1 + num2;
+                break;
+            case "-":
+                result = num1 - num2;
+                break;
+            case "*":
+                result = num1 * num2;
+                break;
+            case "/":
+                if (num2 != 0)
+                {
+                    result = num1 / num2;
+                }
+                else
+                {
+                    Console.WriteLine("Cannot divide by zero.");
+                    return;
+                }
+                break;
+            default:
+                Console.WriteLine("Invalid operator.");
+                return;
+        }
+
+        Console.WriteLine("The result is: " + result);
+    }
+}