MessageBox in C# showing error

Question

I was attempting to add MessageBox.Show(Message); and it was not found in my C# .net web application (button click method and also in Page_Load).An error showing like

'The name 'MessageBox' does not exist in the current context'

Do I need to add any assembly reference for this? (I am using .net framework 4). Is there any alternative method for this?

Answer 1

The key words in your description are

web application

This functionality is only available in client (WinForms, WPF) based applications, not ASP.NET. To do this in a web app you will need to use Javascript, as illustrated in this previous Stack Overflow question.

Answer 2

Use This:

System.Web.UI.ScriptManager.RegisterStartupScript(this, typeof(Page), "alert", "alert('" + Message + "')", true);

Hope This help.

Answer 3

System.Windows.MessageBox is used in WPF applications and System.Windows.Forms.MessageBox is used in Windows Form applications but your project is WebApplication so you don't have access to any of them.

• Newton Sheikh: really!!! all you need to do is add the reference of System.windows.Forms in the project and MessageBox.Show() will work. Try it in any Asp.net application. But I am not sure what will happen after deploying in IIS and then using from non MS-OS
• Hossein Narimani Rad: @NewtonSheikh for more clarification you may have a look at other answers for this post.

Answer 4

The MessageBox class in the System.Windows.Forms namespace is usable from Windows Forms and Not ASP.NET Web Forms.