I have tried making (my first) a C# program:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("hello");
Console.ReadLine();
}
}
}
This goes well, but if I try using System.Windows.Forms:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("hello");
System.MessageBox("hello");
Console.ReadLine();
}
}
}
This is the error I get:
Error 1 The type or namespace name 'Windows' does not exist in the namespace 'System' (are you missing an assembly reference?) C:\Users\Ramy\Documents\Visual Studio 2010\Projects\ConsoleApplication1\ConsoleApplication1\Program.cs 5 14 ConsoleApplication1
Some details:
- I am using Visual Studio 2012;
- I have installed the .NET Development Kit;
- It is a Console Application.
Maybe it's because on a Console Application can't use System.Windows.Forms?
If so, what program should be? I also have tried with a form, but I was only displaying a window and no code.
A console application does not automatically add a reference to System.Windows.Forms.dll.
Right-click your project in Solution Explorer and select Add reference... and then find System.Windows.Forms and add it.
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do so, as none of the solutions I found searching google for days worked for me alone, and seemed to only bring up only outdated tutorials.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
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>
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...
Right click the project, and go to properties.
Change the Target framework from .NET 6.0...to....NET 5.0
Exit back to your code. Which after a few moments will show the System.Windows.Forms connecting properly.
Open back up properties.
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....)
You have to add the reference of the namespace : System.Windows.Forms to your project, because for some reason it is not already added, so you can add New Reference from Visual Studio menu.
Right click on "Reference" ▶ "Add New Reference" ▶ "System.Windows.Forms"
Adding System.Windows.Forms reference requires .NET Framework project type:
I was using .NET Core project type. This project type doesn't allow us to add assemblies into its project references. I had to move to .NET Framework project type before adding System.Windows.Forms assembly to my references as described in Kendall Frey answer.
Note: There is reference System_Windows_Forms available under COM tab (for both .NET Core and .NET Framework). It is not the right one. It has to be System.Windows.Forms under Assemblies tab.
To add the reference to "System.Windows.Forms", it seems to be a little different for Visual Studio Community 2017.
1) Go to solution explorer and select references
2) Right-click and select Add references
3) In Assemblies, check System.Windows.Forms and press ok
4) That's it.
If you're using Visual Studio 2022 open the Project Properties and check the Windows.Forms - Enable Windows Forms for this Project setting.
Ensure Solution Explorer is visible
In MS Studio 2008 Go to view and click Solution explorer
In Solution explorer go to Reference
Right click on Reference and select Add Reference..
Select .NET tab
Scroll down till you find System.Drawing -> select it -> click on OK button
Do the same for System.Windows.Forms
When you run your form this will work
(eddie lives somewhere in time)
go to the side project panel, right click on references -> add reference and find System.Windows.Forms
Any time some error like this occurs (some namespace you added is missing that is obviously there) the solution is probably this - adding a reference.
This is needed because your default project does not include everything because you probably wont need it so it saves space. A good practice is to exclude things you're not using.
may be necesssary,
unreference system.windows.forms
and reference again.
For some reason, none of the solutions worked for me (Windows 11, VS 2022). I actually needed to use the "Windows Form app" template. See: https://learn.microsoft.com/en-us/visualstudio/ide/create-csharp-winform-visual-studio?view=vs-2022.
just add reference to System.Windows.Forms.dll
Related
I have been working on this project in Visual Studio 2010 using C# a few days before Windows 10 update and it worked fine but now when I try to run the program and it tells me the following :
The type or name of the 'Drawing' namespace does not exist in the
'Tekla.Structures' namespace (missing an assembly reference?)
and the same for Tekla.Structures.Model, Tekla.Structures.Model.Operations ... as you can see in the following image:
What I am doing is removing the references and adding them again and in this way the program recognizes it well, but if I clean the solution and try to generate the solution again, the problem arises again ...
What could be the problem?
It seems that you want to use Tekla reference correctly.
I suggest that you can use NugetPackage.
First, right click->References->choose Manage Nuget packages.
Second, choose the Browse->input 'TeklaOpenAPI' in textbox and choose the first.
Third, click install.
Finally after it has been installed, you will see the following correct using code without warning.
first you remove tekla references, select and right click, then remove
remove reference
after right click on References and add reference
add references
after you need add dll corresponding the version you want execute
select references
pay attention when building the app, it only runs in the version you chose the dlls.
I created this program and C# and it worked correctly a few weeks ago.
Now, I copied all of this code to a another project I am working on. I added it to a brand new C# Class inside of the project I am working on. Visual Studio didn't recognize the assembly references that say "not found" in the comments.
This is just bizarre since they were found in the previous program. Does anyone know why Visual Studio can't find these assembly references.
using System;
using System.Collections.Generic;
using System.Linq; //not found
using System.Text;
using XML_Creator; //not found
using System.Xml.Linq; //not found
using System.IO;
An educated guess: It's probably the .NET framework target version of the new project.
System.Linq was introduced on .NET Framework 3.5.
Go to Project -> Properties -> Application and check the Target Framework property. It's probably a target framework prior to 3.5
You need to add refrence to system.Core.
Step 1) Go to your Project Solution Explorer and Select
References
Step 2) Right click it on References and Select Add Reference... a form will appear
Step 3) Search linq on Search bar
Step 4) Now Select/tick the System.XML.Linq checkbox
Step 5) Click Ok
If your file is in App_Code folder, try moving it to another folder. For me its solved the problem.
You need to right click on the solution in Solution Explorer and add a reference to System.Xml.Linq and/or System.Linq in Project Properties.
This has hit me several times - I see it a lot with System.Configuration as well. (For some reason those two references seem to be particularly picky)
For me I tried this and worked:
PROJECT==>Add Reference ==> Browse ==>
C:\Windows\winsxs\x86_netfx35linq-system.core_31bf3856ad364e35_6.1.7601.17514_none_6161fc35ed136622\System.core.dll
Or
you can simply find the System.core.dll using windows search on Os System Drive
I had a similar issue. I upgraded my asp.net project to .NET Framework 4.5.x and it worked. I did tried 4.5.1 first and then later 4.5.0 and both seem to be helping.
I have 2 projects:
ConstrainedScheduleInterfaces
ConstrainedSchedule that has a folder (Testing) with my class that need the reference, here's the code:
Tests.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using
using NUnit.Framework;
using Ninject;
using ConstrainedScheduleInterfaces;
namespace ConstrainedSchedule.Testing
{
internal static class Configuration
{
...........
}
}
I added the reference to the ConstrainedSchedule project, but the using ConstrainedScheduleInterfaces; is marked red as not found.
Both the project has destination framework set .NET Framework 4.5
Any help? Thanks
Does the project contain a reference to the other project? You can't just add the namespace, the project itself needs an assembly reference to the other project which has that namespace.
In Visual Studio, open the Solution Explorer. Right-click on the ConstrainedSchedule project and select something along the lines of "Add Reference." In the dialog, select project references (depending on the version of Visual Studio it may be a tab or some other interface indicating projects as part of the solution). Select the ConstrainedScheduleInterfaces project and add the reference.
More information here.
For other people who have this problem, who have already added the reference to the dll and have made sure you have the right namespace at the top, I've found another thing that can cause this.
Select-click the file in visual studio and choose properties. In the Advanced part of properties, look for Build Action. Change it to compile if it's not already on that, and try to build again.
There might be another reason: different target frameworks.
My main project had ".NET Framework 4.7.2" and the referenced project (linked from another solution) had ".NET Framework 4.5.1".
Select the project properties and change the target framework.
I was having this issue after renaming a project and namespace due to a naming conflict.
Basically my main project had a reference to a project I made called Common, but then I needed to reference another project called Common that another dev had written. After renaming my project something like SpecificCommon, I was able to have references to both Common and SpecificCommon in my main project. However, all references to SpecificCommon namespace were now broken.
At first I thought this was some problem with the namespace refactor, but it turns out that it was because SpecificCommon and Common both still had the same assembly name (Common.dll). Changing the assembly name in SpecificCommon's properties and rebuilding solved the issue for me.
In C#, I made a ClassLibrary that has one Namespace and one Class.
I saved it and build it.
in other Projects, when i use it, I add it to my references by browsing to the .dll location.
But The Problem is that its name is not showing up in the Intellisense.
i.e when I: using ... my dll doesn't show ..
I'm Importing the library to a ConsoleApp.
both of the App and the library target Framework is .NET Framework 4.0
and I made their Assembly Version 4.0.0.0 so they're the exact same.
is there a setting or something that I'm missing ?
how can i make it pop up ?
I'm using VS2010 Professional
Thank you for your help
Maybe this be usefull, I was having a similar issue, I have a Web project, add the reference to a Class Library by selecting the project, but if I made a change on the class library, I can´t see that change on the intellisense of the Web Project, after try many things, I see that in the recently added reference, the value of the option "Local Copy" was set "True", then I change it to false and everething works!
I had a similar issue but in my case it was a property on the class. If you go to the file properties and look for a Build Action. Somehow mine was set to Content it had to be set to Compile.
I am using Visual Studio 2013. I hope this helps someone else.
Is the namespace for your assembly different than the namespace for your currently open project? I've had times when the current project and an assembly share the same namespace path the intellisense can mess up.
In general, Visual Studio is pretty good about intellisense generation, especially for C#. But sometimes there are some interesting conditions regarding ambiguities, and especially mixing project types where it just doesn't quite work.
Placing your content in the same namespace makes me wonder if you've actually fixed the problem (it may just be autocompleting the namespace in the currently loaded project rather than the assembly), but if it allows you to continue working, then go with it!
Right click on project on which you add reference of your dll/project select menu project dependancies and select/MarkCheckBox for reference project/dll. then it will work fine.
If the class library project had its name changed after creation, then intellisense may fail finding it due to directory issues, I believe.
I created my class with the generic "ClassLibrary1" or whatever, and then later changed the default namespace, class name, and project name inside of VS2017. I closed VS2017 and changed the directory name to match my default namespace, and then re-associated the project file in VS2017, and then re-added the reference in my main project file.
All seems to be fixed now.
Image Dummy = Image.FromFile("image.png");
Dummy.Save("image.bmp", ImageFormat.Bmp);
what the question says
i have these
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
but i get an error saying that the namespace drawing does not exist in the namespace system :/
Add a reference to System.Drawing
When you use using statements, this lets the compiler know that when you say Image you really mean System.Drawing.Image for example.
However, now the compiler needs to know where System.Drawing is. By default, in Visual Studio, you will probably already reference System, System.Data, and System.Xml.
Now you are writing for System.Drawing. Right-click the project in the project browser, and select "Add reference...". This will present you with a tabbed interface that lets you select one of:
A .NET Reference. Any assembly in the GAC will be listed here. Scroll down and select System.Drawing for example.
COM Reference. For interfacing with non-.NET, yet very Windows components.
Projects. A Visual Studio nicety. Reference a DLL that has not been built yet. Select a project within the same solution. Intellisense before you compile.
Browse (for a file). If a .NET component or other type with exported definitions has already been built, you can reference the DLL from here.
Adding the "using" is only part of the equation. You also have to reference the DLL which contains the code you want to use.
For example, if you write a cool library under the namespace com.shuttleu.awesomelib, I could have the following at the top of my C# file:
using com.shuttleu.awesomelib;
On its own, that won't do me any good, I have to reference the DLL (referred to as an "assembly") in my project. You do that by right-clicking the project and selecting "Add Reference..."
In addition to the using statement, you also need to add the System.Drawing DLL (called an 'assembly') as a reference in your Visual Studio project. To do that, in the Solution Explorer pane usually at the right (if it's not open, go to View --> Solution Explorer), right click References and click Add Reference. In the .NET tab (open by default), scroll down until you see System.Drawing, select it, and click OK. After doing that, System.Drawing should appear under References in the Solution Explorer, and the using statement will now point to the correct DLL, therefore your code will work. :)
"Adding the "using" is only part of the equation. You also have to reference the DLL which contains the code you want to use"
Just curious--why do we have to do both for a console app, while in an VB.Net web app, the text "Imports System.Drawing" is sufficient?