C#  

Sort a list of integers in ascending/descending order

Step 1: Design Page – SortList.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SortList.aspx.cs" Inherits="SortList" %>

<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Sort List Ascending / Descending - Real Time Example</title>
    <style>
        body {
            font-family: Arial;
            background-color: #f2f5fc;
            margin: 50px;
        }
        .container {
            width: 500px;
            margin: auto;
            background: #fff;
            border-radius: 10px;
            box-shadow: 0 0 10px #ccc;
            padding: 25px;
        }
        h2 {
            color: #1A2A80;
            text-align: center;
        }
        .form-control {
            width: 100%;
            padding: 8px;
            margin-top: 10px;
        }
        .btn {
            background-color: #7A85C1;
            color: white;
            border: none;
            padding: 10px;
            border-radius: 5px;
            cursor: pointer;
            width: 48%;
        }
        .btn:hover {
            background-color: #5b68a1;
        }
        .button-group {
            display: flex;
            justify-content: space-between;
            margin-top: 15px;
        }
        .result {
            margin-top: 20px;
            font-weight: bold;
            text-align: center;
            color: #333;
            white-space: pre-line;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
        <div class="container">
            <h2>Sort List of Integers</h2>

            <asp:Label ID="Label1" runat="server" Text="Enter Numbers (comma separated):"></asp:Label><br />
            <asp:TextBox ID="txtNumbers" runat="server" CssClass="form-control" placeholder="Example: 45,12,89,3,20"></asp:TextBox>

            <div class="button-group">
                <asp:Button ID="btnAscending" runat="server" Text="Ascending" CssClass="btn" OnClick="btnAscending_Click" />
                <asp:Button ID="btnDescending" runat="server" Text="Descending" CssClass="btn" OnClick="btnDescending_Click" />
            </div>

            <asp:Label ID="lblResult" runat="server" CssClass="result"></asp:Label>
        </div>
    </form>
</body>
</html>

Step 2: Backend Logic – SortList.aspx.cs

using System;
using System.Collections.Generic;

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

    // Sort Ascending
    protected void btnAscending_Click(object sender, EventArgs e)
    {
        try
        {
            string input = txtNumbers.Text.Trim();

            if (string.IsNullOrEmpty(input))
            {
                lblResult.Text = "Please enter numbers separated by commas.";
                lblResult.ForeColor = System.Drawing.Color.Red;
                return;
            }

            // Split input and convert to integers
            string[] parts = input.Split(',');
            List<int> numbers = new List<int>();

            foreach (string s in parts)
            {
                numbers.Add(Convert.ToInt32(s.Trim()));
            }

            // Sort ascending
            numbers.Sort();

            lblResult.Text = "Sorted in Ascending Order:\n" + string.Join(", ", numbers);
            lblResult.ForeColor = System.Drawing.Color.Green;
        }
        catch
        {
            lblResult.Text = "Invalid input! Please enter only numbers separated by commas.";
            lblResult.ForeColor = System.Drawing.Color.Red;
        }
    }

    // Sort Descending
    protected void btnDescending_Click(object sender, EventArgs e)
    {
        try
        {
            string input = txtNumbers.Text.Trim();

            if (string.IsNullOrEmpty(input))
            {
                lblResult.Text = "Please enter numbers separated by commas.";
                lblResult.ForeColor = System.Drawing.Color.Red;
                return;
            }

            string[] parts = input.Split(',');
            List<int> numbers = new List<int>();

            foreach (string s in parts)
            {
                numbers.Add(Convert.ToInt32(s.Trim()));
            }

            // Sort ascending first, then reverse
            numbers.Sort();
            numbers.Reverse();

            lblResult.Text = "Sorted in Descending Order:\n" + string.Join(", ", numbers);
            lblResult.ForeColor = System.Drawing.Color.Green;
        }
        catch
        {
            lblResult.Text = "Invalid input! Please enter only numbers separated by commas.";
            lblResult.ForeColor = System.Drawing.Color.Red;
        }
    }
}

Real-Time Example Output

Input

45, 12, 89, 3, 20

Output 1 (Ascending Button Clicked)

Sorted in Ascending Order:
3, 12, 20, 45, 89

Output 2 (Descending Button Clicked)

Sorted in Descending Order:
89, 45, 20, 12, 3

Explanation

KeywordUsage
List<int>Stores integers entered by user
Split(',')Splits user input into string array
Convert.ToInt32()Converts each string to integer
Sort()Sorts list in ascending order
Reverse()Reverses list to descending order
string.Join()Combines list into single string for display

Algorithm

1. Read comma-separated numbers from textbox.
2. Split the input using ','.
3. Convert each value to integer and add to list.
4. If Ascending → call Sort().
5. If Descending → call Sort() then Reverse().
6. Display sorted list in label.

Output Example Table

InputButton ClickedOutput
10, 2, 30, 5Ascending2, 5, 10, 30
10, 2, 30, 5Descending30, 10, 5, 2
5, 9, 1Ascending1, 5, 9

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