How to draw a hollow rectangle with it's diagonals in the console

Question

I want to draw a hollow rectangle with it's diagonals. The height of rectangle should be greater than 5 and at most 20. The witdh should be also greater than 5 and at most 80. I already got this code:

using System;

public class Test
{
    public static void Main()
    {
        Console.Write("Enter width of rectangle: ");
        int w = int.Parse(Console.ReadLine()); 
        Console.Write("Enter height of rectangle: ");
        int h = int.Parse(Console.ReadLine()); 
        Console.WriteLine();
        if(w > 5 && w <= 80 && h > 5 && h <= 20)
        {

            draw(w, h);
        }
        else
        {
            Console.WriteLine("Invalid entry!");
        }
    }
    static void draw(int w, int h)
    {
        for (int i = 0; i < h; i++)
        {
            for (int j = 0; j < w; j++)
            {
                if ((i == 0) || (j == 0) || (i == h - 1) || (j == w - 1)   || (i == j)  || (i + j == w - 1) )
                {
                    Console.Write("*");
                }
                else
                {
                    Console.Write(" ");
               }

            } Console.WriteLine();
        }
    }
}

But this code draws correctly only for squares. For rectangles it doesn't draw diagonals correctly. Any help would be greatly appreciated.

Answer 1

When the rectangle is not a square you have to take in account the ratio between the width and the height. You could do it like this:

using System;

public class Test
{
    static int width;
    static int height;

    public static void Main()
    {
        Console.Write("Enter width of rectangle: ");
        width = int.Parse(Console.ReadLine()); 
        Console.Write("Enter height of rectangle: ");
        height = int.Parse(Console.ReadLine()); 
        Console.WriteLine();
        if(width > 5 && width <= 80 && height > 5 && height <= 20)
        {
            draw();
        }
        else
        {
            Console.WriteLine("Invalid entry!");
        }
    }

    static void draw()
    {
        Console.WriteLine((float)width/(float)height);
        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                if (IsBorder(x, y)  || IsDiagonal(x, y))
                {
                    Console.Write("*");
                }
                else
                {
                    Console.Write(" ");
               }

            } Console.WriteLine();
        }
    }

    static bool IsBorder(int x, int y)
    {
        return x == 0 
            || y == 0  
            || x == width - 1  
            || y == height - 1;
    }

    static bool IsDiagonal(int x, int y)
    {
        return width < height  
            ? IsDiagonalHigh(x, y)  
            : IsDiagonalWide(x,y);
    }

    static bool IsDiagonalHigh(int x, int y)
    {
        var aspectRatio = (float)width / (float)height;
        return x == (int)(y * aspectRatio) 
            || x == width - (int)(y * aspectRatio) - 1;
    }

    static bool IsDiagonalWide(int x, int y)
    {
        var aspectRatio = (float)height / (float)width;
        return y == (int)(x * aspectRatio)  
            || y == (int)((width - x - 1) * aspectRatio);
    }

}

As you can see I took the liberty to change w and h to the static fields width and height .