Shows red mark on MessageBox.Show

Question

When I type - MessageBox.Show("Deleted!");

The C# editor red marks the 'MessageBox.Show' and shows

'The name MessageBox.Show doesn't exist in the current context. '

I have used 'using System.Windows.Forms;' Here also it red marks the 'Forms'.

Please Help Me. Thanks.

Which type of application is this? Is it console app or WinForm app or WPF app? — Keyur Ramoliya, Oct 12 '18 at 05:24
Please give us - if possible - the complete source code of your application. — user11909, Oct 12 '18 at 05:25
he is a new contributor, please modify the post instead of vote down — Anas Alweish, Oct 12 '18 at 05:37
@AnasAlweish OP being a new contributor means taking extra care to explain Stack Overflow and nicely point out what is missing in a post, which has been done by previous comments. It does _not_ mean other users shouldn't downvote. Downvotes are not unfriendly. — Modus Tollens, Oct 12 '18 at 05:48

Arphile · Answer 1 · 2018-10-12T05:29:32.373

0

You need to include namespace top of the script.

Winform >

using System.Windows.Forms;

WpfForm >

using System.Windows;

Edited :

Since you added it's console app, you need to do additional things.

Right click 'Reference' on your project and click add

Search System.Windows.Forms and add it.

after that, you can include System.Windows.Forms and use it.

edited Oct 12 '18 at 05:29

answered Oct 12 '18 at 05:26

Arphile

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1. There isn't a thing called "WpfForm"; 2. OP already said that he has the using directive. – Sebastian Hofmann Oct 12 '18 at 05:29

score 0 · Accepted Answer · answered Oct 12 '18 at 05:26

As you've deduced, MessageBox does indeed belong to System.Windows.Forms. Unless you have created a Windows Forms project, the reference to this library will not automatically be added to your project.

You can add it to other project types by doing this:

Right-click "References" under your project in the Solution Explorer
Click "Add reference"
Select "Assemblies"
Check "System.Windows.Forms"
Finally, click OK.

After doing this, your using System.Windows.Forms should no longer show the red underline, and your message box code should work. Note that normally console output would be output to the console and not to a messagebox, hence why it isn't available by default.

I don't believe message box functionality is available in .NET Core or .NET Standard (see here), so if you made a .NET Core Console Application (as opposed to .NET Framework), you might want to output information in a different way.

score 0 · Answer 3 · answered Oct 12 '18 at 05:27

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You have to add a Reference on "System.Windows.Forms" in your project references.

Right click on "References" folder, select Add. Then Chose "Assemblies", then search for System.Windows.Forms and add the reference to your project.

answered Oct 12 '18 at 05:27

user11909

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Shows red mark on MessageBox.Show

3 Answers3