C#

string[] size = new string[3];//declare a string array of 3 elements

                size[0] = "thin crust"; //declare the quality
                size[1] = "medium crust";
                size[2] = "thick crust";

                Console.WriteLine("Enter type of pizza required: 1 = thin crust, 2 = medium crust, 3 = thick crust: ");
                int result = int.Parse(Console.ReadLine());
                Console.WriteLine("You have chosen the {0} pizza", size[result - 1]);
                Console.ReadLine();
            }

        areaM2://diameter size of pizza
                {
                    float x;
                    Console.Write("Please enter number, between 100 and 1000: ");
                    x = float.Parse(Console.ReadLine());
                    if ((x >= 100f) && (x <= 1000f))
                    {
                        Console.WriteLine("Your number {0} is between 100 and 1000", x);
                        Console.ReadLine();
                    }

                    else
                    {
                        Console.WriteLine("You did not enter a valid number: ");
                        Console.ReadLine();
                        goto areaM2;
                    }
             
                }
        
                size[0] = 2.5; //declare fixed pizza price 
                size[1] = 5;
                size[2] = 7.5;

            //(fixed charge + area(m2) x £30) or Pi x r2 x 30.

                x = x * x;
                Console.ReadLine();