Как добавить using system windows forms

For Those using Visual Studio 2022 with .Net Core 6.0

Sorry to revive this thread, but I created an account just to do so, as none of the solutions I found searching google for days worked for me alone, and seemed to only bring up only outdated tutorials.

Not Working =(

What DID work for me

1. Double click your project (opening the csproj editor window)

Add the following lines (replacing the existing TargetFramework line):

<TargetFramework>net6.0-windows</TargetFramework>
<UseWindowsForms>true</UseWindowsForms>

My window, for referrence, looks like:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0-windows</TargetFramework>
      <UseWindowsForms>true</UseWindowsForms>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

1. Note Both lines! I read several solutions / videos that stopped simply after adding the «UseWindowsForms» tag, which did not solve the problem for me, even after unloading and reloading/closing and opening etc.

I stumbled on this solution after applying the «UseWindowsForms» tag, and then in desperation changing my NET framework in properties to 5.0, which caused it to work, and then noted when changing back to 6.0 it still worked.

If you forget the Framework tag in the future, you can reproduce the effect just by flipping your properties back and forth…

1. Right click the project, and go to properties.

2. Change the Target framework from .NET 6.0…to….NET 5.0

3. Exit back to your code. Which after a few moments will show the System.Windows.Forms connecting properly.

4. Open back up properties.

5. Change the Target framework from .Net 5.0, back to .Net 6.0

Congratulations

You have (or at least I have) a .Net 6.0 project that is properly allowing me to use System.Windows.Forms (Including the Clipboard, which I suspect many here are looking for…).

I did due diligence on this, testing it multiple times across multiple projects, and it (at least for my setup) consistently works!

BTW. For those wondering. the [STAThread] Attribute tag seen in the pictures is needed to allow the Clipboard class to function. (this is also why I am not using top level statements in the example, but if you don’t need that Class, the example works with top level statements (I needed it to show my Clipboard test….)

For Those using Visual Studio 2022 with .Net Core 6.0

Sorry to revive this thread, but I created an account just to do so, as none of the solutions I found searching google for days worked for me alone, and seemed to only bring up only outdated tutorials.

Not Working =(

What DID work for me

1. Double click your project (opening the csproj editor window)

Add the following lines (replacing the existing TargetFramework line):

<TargetFramework>net6.0-windows</TargetFramework>
<UseWindowsForms>true</UseWindowsForms>

My window, for referrence, looks like:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0-windows</TargetFramework>
      <UseWindowsForms>true</UseWindowsForms>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

1. Note Both lines! I read several solutions / videos that stopped simply after adding the «UseWindowsForms» tag, which did not solve the problem for me, even after unloading and reloading/closing and opening etc.

I stumbled on this solution after applying the «UseWindowsForms» tag, and then in desperation changing my NET framework in properties to 5.0, which caused it to work, and then noted when changing back to 6.0 it still worked.

If you forget the Framework tag in the future, you can reproduce the effect just by flipping your properties back and forth…

1. Right click the project, and go to properties.

2. Change the Target framework from .NET 6.0…to….NET 5.0

3. Exit back to your code. Which after a few moments will show the System.Windows.Forms connecting properly.

4. Open back up properties.

5. Change the Target framework from .Net 5.0, back to .Net 6.0

Congratulations

You have (or at least I have) a .Net 6.0 project that is properly allowing me to use System.Windows.Forms (Including the Clipboard, which I suspect many here are looking for…).

I did due diligence on this, testing it multiple times across multiple projects, and it (at least for my setup) consistently works!

BTW. For those wondering. the [STAThread] Attribute tag seen in the pictures is needed to allow the Clipboard class to function. (this is also why I am not using top level statements in the example, but if you don’t need that Class, the example works with top level statements (I needed it to show my Clipboard test….)

It looks like you are trying to use the Forms namespace from the System.Windows namespace in your visual-studio-2019 project, but you are getting an error message saying that it does not exist in the namespace.

One possibility is that you are missing a reference to the System.Windows.Forms assembly in your project. To add this reference, you can try the following steps:

1. Right-click on your project in the Solution Explorer window and select “Add Reference” from the context menu.

2. In the “Reference Manager” window that appears, select the “Assemblies” tab.

3. Search for “System.Windows.Forms” in the search box or browse through the list of available assemblies until you find it.

4. Check the box next to “System.Windows.Forms” to select it, and then click the “Add” button at the bottom of the window.

5. Once the reference has been added, try rebuilding your project and see if the error message disappears.

If the “References” tab still does not appear in the Solution Explorer window, you may need to customize your view settings. You can do this by clicking the “Options” button at the top of the Solution Explorer window and selecting “Show all files”.

Alternatively, you can try adding the reference manually by editing your project file (*.csproj) in a text editor. Look for the <Reference> element and add the following line inside it:

<HintPath>path\to\System.Windows.Forms.dll</HintPath>

Replace “path\to” with the actual file path where the System.Windows.Forms.dll assembly is located on your system.

Hopefully, one of these steps will help you resolve the issue and get “using System.Windows.Forms” to work in your project.