public static void Main(string[] args)
Console.WriteLine("Area of various geometrical shape. \n----------------------------------");
Console.WriteLine("[1] Area of Circle\n[2] Area of Rectangle\n[3] Area of Triangle");
Console.Write("Enter your option: ");
inputOption = Console.ReadLine();
if (Int32.TryParse(inputOption, out numberOption) == true)
Console.Write("Enter radius of circle: ");
inputRadius = Console.ReadLine();
if (Double.TryParse(inputRadius, out numberRadius) == true)
Console.WriteLine("Input error. Zero or negative value of radius is not allowed.");
double area = 3.1416 * (numberRadius * numberRadius);
Console.WriteLine("The area of circle is {0:#,0.0000}.", area);
Console.WriteLine("Invalid radius. Please input a valid value of radius.");
Console.Write("Enter Length of the Rectangle: ");
inputLength = Console.ReadLine();
if (Double.TryParse(inputLength, out numberLength) == true)
Console.WriteLine("Input error. Zero or negative value of length is not allowed. ");
Console.Write("Enter Width of the Rectangle: ");
inputWidth = Console.ReadLine();
if (Double.TryParse(inputWidth, out numberWidth) == true)
Console.WriteLine("Input error. Zero or negative value of width is not allowed.");
double area = numberWidth * numberLength;
Console.WriteLine("The area of the rectangle is {0:#,0.0000}.", area);
Console.WriteLine("Invalid Width. Please input a valid value of Width.");
Console.WriteLine("Invalid length. Please input a valid value of length.");
Console.Write("Enter Base of the Triangle: ");
inputBase = Console.ReadLine();
if (Double.TryParse(inputBase, out numberBase) == true)
Console.WriteLine("Input error. Zero or negative value of Base is not allowed.");
Console.Write("Enter Height of the Triangle: ");
inputHeight = Console.ReadLine();
if (Double.TryParse(inputHeight, out numberHeight) == true)
Console.WriteLine("Input error. Zero or negative value of Height is not allowed.");
double area = (numberBase * numberHeight)/2;
Console.WriteLine("The area of the triangle is {0:#,0.0000}.", area);
Console.WriteLine("Invalid height. Please input a valid value of height.");
Console.WriteLine("Invalid Base. Please input a valid value of Base.");
Console.WriteLine("Input error. Please select from 1 - 3 only.");
Console.WriteLine("Invalid option. Please select from 1 - 3 only.");