📅 ASP.NET – Calendars – Beginner’s Guide to Using the Calendar Control with Code & Output
🧲 Introduction – What Is the ASP.NET Calendar Control?
The ASP.NET Calendar Control is a built-in Web Forms component that lets users view dates, select specific days, and interact with the calendar through server-side C# code. It’s ideal for scheduling, bookings, event reminders, and forms that require date selection.
ASP.NET handles date formatting, navigation, selection, and styling without writing any JavaScript.
🎯 In this guide, you’ll learn:
- How to display and interact with the Calendar control
- How to get the selected date in C#
- How to respond to selection and change events
- Full working code with beginner-friendly explanations and output
📂 ASP.NET Web Forms File Structure
| 📁 File Name | 📘 Description |
|---|---|
CalendarDemo.aspx | Markup file where you add the calendar and other controls |
CalendarDemo.aspx.cs | Code-behind file where you handle logic like date selection |
📄 Step 1: Markup File – CalendarDemo.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="CalendarDemo.aspx.cs" Inherits="CalendarDemo.CalendarDemo" %>
<html>
<body>
<form id="form1" runat="server">
<h3>📅 ASP.NET Calendar Control Demo</h3>
<!-- Calendar Control -->
<asp:Calendar ID="Calendar1" runat="server" OnSelectionChanged="Calendar1_SelectionChanged" />
<br /><br />
<!-- Label to show selected date -->
<asp:Label ID="lblSelectedDate" runat="server" Font-Size="Larger" ForeColor="Blue" />
</form>
</body>
</html>
🔍 Explanation of Each Element
| Control | 💡 Purpose |
|---|---|
<asp:Calendar ... /> | Displays a calendar (month view by default) |
OnSelectionChanged | Event that fires when user selects a new date |
lblSelectedDate | Shows the selected date using C# backend code |
⚙️ Step 2: Code-Behind File – CalendarDemo.aspx.cs
public partial class CalendarDemo : System.Web.UI.Page
{
protected void Calendar1_SelectionChanged(object sender, EventArgs e)
{
// Get the selected date
DateTime selected = Calendar1.SelectedDate;
// Show it in a label
lblSelectedDate.Text = "You selected: " + selected.ToString("dddd, MMMM dd, yyyy");
}
}
🔍 Beginner Explanation of Code
| Code | 💬 What It Does |
|---|---|
Calendar1.SelectedDate | Gets the date the user clicked in the calendar |
ToString("format") | Converts the DateTime into readable format like “Monday, March 11, 2025” |
lblSelectedDate.Text | Updates the label to show the chosen date |
🖥️ Output Preview in Browser
▶️ On Initial Page Load:
📅 [Calendar displayed for current month]
(No message yet)
▶️ After Selecting March 11, 2025:
📅 [March calendar with 11th selected]
You selected: Tuesday, March 11, 2025
✅ The label automatically updates when a new date is selected.
📌 Summary – Recap & Takeaways
The ASP.NET Calendar control is perfect for date-based forms like bookings, events, and reminders.
🔍 Key Learnings:
<asp:Calendar>displays a calendar and raises events when a date is selected- You use
Calendar1.SelectedDateto get the selected date in C# - Output can be customized using standard C#
DateTimeformatting - You can dynamically show messages based on selected dates
✅ Common uses:
- Hotel bookings
- Event scheduling
- Attendance forms
- Delivery date pickers
❓ Frequently Asked Questions (FAQs)
❓ Can I set a default selected date in the Calendar?
✅ Yes. In Page_Load, use:
Calendar1.SelectedDate = DateTime.Today;
❓ How can I highlight today’s date or disable past dates?
✅ You can use the DayRender event for custom logic:
protected void Calendar1_DayRender(object sender, DayRenderEventArgs e)
{
if (e.Day.Date < DateTime.Today)
e.Day.IsSelectable = false;
}
❓ What format does SelectedDate.ToString() return?
✅ It returns the full datetime. Use .ToString("d") for short format or "MMMM dd, yyyy" for long date.
❓ Can I style the calendar with CSS?
✅ Yes! Use CssClass and style with custom CSS, or set inline styles like BackColor, Font-Bold, etc.
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