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.
Related
I am working on a c# project. It reference quite a few packages and there are packages referencing other packages. So a namespace used in the program does not necessarily come from a direct reference.
For a specific using statement, is there a way to find out which reference (by reference, I mean the external DLL's/NuGet packages) it is originated from?
Thank you.
For example project reference a Nuget Package called Package1. In Package1 we have namespace called Namespace1. Then Package1 references Package2, which have a namespace called Namespace2.
In your code you could have
using Namespace2;
But how do you know which assembly or Nuget Package Namespace2 is originated from (in this case Package1)?
I'm not aware of a native means in Visual Studio to do this. However, JetBrains ReSharper can do this. Note that a single namespace import isn't tied to a single assembly. A namespace import (using statement) can easily bring types from several different assemblies into scope.
With ReSharper in hand I simply selected the namespace and pressed F12. You can see that System.Collections.Generic is defined in four assemblies referenced by this project.
I tried harlam357's answer in visual studio 2019 but it failed (the image bellow).
1.
Then, I did a trick. I turned the reference in to a comment and found the error line which implements a method belong the namespace. Through the method I got the root reference.
2.
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 am still trying to get my head around namespaces in referenced projects.
I have a c# project where a namespace ("A") is defined.
I create a F# application, where I reference the c# project.
open A
leads to the following:
error FS0039: The namespace or module 'A' is not defined
This is what I have checked:
The C# and F# project target the same framework (.Net Framework 4.5) (F# the namespace or module 'XXXX' is not defined)
The C# and F# project have the same target (Any CPU)
The C# project is correctly listed among the F# project references
I am correctly trying to open a namespace (not as in this case: How to use C# object from F#?)
I am not operating from the FSI (https://connect.microsoft.com/VisualStudio/feedback/details/632859/difference-in-namespace-reference-between-f-interactive-and-compiled-exe)
MSDN is not much of a help (http://msdn.microsoft.com/en-us/library/vstudio/dd393787.aspx).
Thanks.
[EDIT]
I have started from scratch, so that the example is lean and clean.
The C# project "ClassLibrary1" contains:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ClassLibrary1
{
public class Class1
{
}
}
The F# Application is:
// Learn more about F# at http://fsharp.net
// See the 'F# Tutorial' project for more help.
open ClassLibrary1
[<EntryPoint>]
let main argv =
printfn "%A" argv
0 // return an integer exit code
The error:
The namespace or module 'ClassLibrary1' is not defined
Make sure your reference is a real project references and not just referencing the DLL in the bin\Debug folder.
If you can't get a real project reference to work, make sure the F# project is set to depend on the C# project so that it gets built first by Visual Studio (right-click on the project and go to Project Dependencies then use the tickboxes).
I had this same issue. All I had to do was make sure my C# project dependencies were all settled, build my C# projects, then the F# project was able to reference the correct dll's.
In Visual Studio, you can right click on each C# project and press build.
In VSCode, you have to use the terminal to navigate to each project and run dotnet build.
I am trying to create a class library using some classes that I created in another project. One of the classes uses images and needs the System.Drawing namespace. However, when I try to copy the code from my project into a new class in my class library, I get an error saying the image object does not exist in the current context, and
The type or namespace name "Drawing" does not exist in the namespace System(are you missing a using directive or an assembly reference?)
It works fine in the other class as part of the other project. Why would this be?
Make sure that System.Drawing is added to the library's assembly references. By default, for class libraries, no Windows Forms assemblies are added.
Yes The problem lies in the References. If you go to your Solution Explorer and expand it, you will see a nested Folder Titled 'References'. Here is where you add the references needed in your project. To add them, simply right click the folder and select add Reference. Once here the reference you need will be in the .Net tab.
In case if a particular .NET reference is not added by default, do that manually:
using System.Drawing;
Write this in top of your class file. then also if u get error right click on reference and add reference of System.Drawing in your project.
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