C#  

Print Diamond Star Pattern in C# using ASP.NET WebForms

Introduction

Pattern printing is one of the best ways to understand loops, nested iterations, and conditional logic in C#.
In this article, we’ll create a Diamond Star Pattern using ASP.NET WebForms, which combines both the Pyramid and Inverted Pyramid logic.

Pattern to Print

If the user enters 5, the output will look like this:

    *
   * *
  * * *
 * * * *
* * * * *
 * * * *
  * * *
   * *
    *

C# WebForms Real-Time Example

ASPX Page (DiamondPattern.aspx)

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="DiamondPattern.aspx.cs" Inherits="WebApp.DiamondPattern" %>

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Diamond Star Pattern in C# WebForms</title>
</head>
<body>
    <form id="form1" runat="server">
        <div style="font-family: Arial; margin: 50px;">
            <h2>Diamond Star Pattern</h2>
            <asp:Label ID="Label1" runat="server" Text="Enter number of rows: " />
            <asp:TextBox ID="txtRows" runat="server"></asp:TextBox>
            <asp:Button ID="btnGenerate" runat="server" Text="Generate Pattern" OnClick="btnGenerate_Click" />
            <br /><br />
            <asp:Label ID="lblResult" runat="server" Font-Names="Consolas" Font-Size="Large"></asp:Label>
        </div>
    </form>
</body>
</html>

Code-Behind (DiamondPattern.aspx.cs)

using System;
using System.Text;

namespace WebApp
{
    public partial class DiamondPattern : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
        }

        protected void btnGenerate_Click(object sender, EventArgs e)
        {
            int rows;
            if (int.TryParse(txtRows.Text, out rows) && rows > 0)
            {
                lblResult.Text = GenerateDiamond(rows);
            }
            else
            {
                lblResult.Text = "Please enter a valid positive number.";
            }
        }

        private string GenerateDiamond(int rows)
        {
            StringBuilder pattern = new StringBuilder();

            // Upper pyramid
            for (int i = 1; i <= rows; i++)
            {
                // Print spaces
                for (int j = i; j < rows; j++)
                {
                    pattern.Append("&nbsp;&nbsp;");
                }

                // Print stars
                for (int k = 1; k <= (2 * i - 1); k++)
                {
                    pattern.Append("*");
                }

                pattern.Append("<br/>");
            }

            // Lower inverted pyramid
            for (int i = rows - 1; i >= 1; i--)
            {
                // Print spaces
                for (int j = rows; j > i; j--)
                {
                    pattern.Append("&nbsp;&nbsp;");
                }

                // Print stars
                for (int k = 1; k <= (2 * i - 1); k++)
                {
                    pattern.Append("*");
                }

                pattern.Append("<br/>");
            }

            return pattern.ToString();
        }
    }
}

Explanation

  1. User Input
    The user enters a number of rows in the textbox (e.g., 5).

  2. Button Click Event
    When the “Generate Pattern” button is clicked, the program calls GenerateDiamond() method.

  3. Logic Breakdown

    • The first loop (Upper Pyramid) prints stars increasing from 1 → N.

    • The second loop (Lower Pyramid) prints stars decreasing from N-1 → 1.

    • &nbsp; adds spacing in HTML.

    • <br/> adds line breaks for each row.

  4. Output Display
    The full diamond shape is displayed in the lblResult label using HTML formatting.

Example Output (for input 5)

        *
      ***
    *****
  *******
*********
  *******
    *****
      ***
        *

(Spaces appear correctly in browser due to &nbsp;.)

Key Concepts

  • Nested Loops: Used to control the number of spaces and stars.

  • StringBuilder: Efficient for string concatenation in loops.

  • HTML Encoding: &nbsp; used for spacing since browsers ignore multiple spaces.

Real-Time Usage

  • Often used in educational web applications for teaching loop concepts.

  • Helps beginners visualize patterns and control flow in C#.

  • Can be used in coding challenge portals built using ASP.NET.

Conclusion

This program demonstrates how to use nested loops, HTML formatting, and recursion-like logic flow to generate a Diamond Star Pattern dynamically in C# WebForms.

It’s a perfect learning project to understand loop structures and pattern printing in ASP.NET.

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