Very new to C#/VS and this is vexing me - there are a lot of similar questions on SO, but none seem specific enough to help me!
I'd like to use a class from ProjectA in another class (eg ProjectB). I wish to "maintain" the class in the original project, ProjectA, and simply "use" it in Project B (if that makes sense?!)
From what I have read here and elsewhere, I first need to set up a reference to ProjectA within Project B - but this is the stage I am struggling with.
When I follow what I have read (eg on How to use a Class from one C# project with another C# project ) I get to the stage where I am in the "Add References" dialog, and have selected "Projects".
But VS wants me to reference specific "Component" file types (.dll, .tld, .olb, .ocx, .exe) but I can't seem to find a file that refers to "ProjectA". I browse to the folder where ProjectA sits, but no files of the correct type exist. There are files such as:
ProjectA.csproj, ProjectA.sln, ProjectA.suo
but none of these can be selected in the dialog.
Can anyone provide what I suspect will be a very simple answer? Thanks!
In the dialog box for Add Reference you have the option to reference a project within the solution. This will add all its namespace classes and make them available for your use in the other project. You need to make the two projects part of the same solution to be able to do that.
A project with an output type of class library cannot be started
directly. In order to debug this project, add an executable project to
this solution which references the library project. Set the executable
project as the startup project.
While running the program in C# visual studio 2010 I am getting this error. Please tell me how to sort out this error?
Set your startproject in the project explorer by clicking right mouseclick on an executable project and choose "Set as start project"
You created the project as a class library project, not an executable program. Class libraries are compiled and then used by other applications for common functionality.
If you meant to create a class library, you need to create a test application (or, better yet, Unit Tests) to test the functionality. If you meant to create an executable application, you'll need to modify the project.
If you have multiple projects in a single solution, you might also need to make sure you have the correct project set as the "Start Project" rather than one of the class library projects.
what you have done is that you have made a class library with all your code
every project in .Net needs a starting point like Main() function in c# which obsly isnt present in a class libraty type of project
what you can do instead is
1. Make a console project inside the same solution. by right clicking the solution and add new project
2. Add a reference to the class library
3. Access the classes/methods of the class library and then starting the console project instead of class library project
Alternatively,
If you have a console project OR any other project in the solution already
right click the project in the solution explorer and Set as Startup project
Right click on Solution-->Go to properties-->Expand Common properties tab-->(On right side) Select Radio button with option Single startup project-->choose project from drop down list.
Enjoy.
If you want to debug code in the DLL or run it using tests, go to the properties of the project, go to the Debug tab, select "Start external program" and enter the name of the application to use, such as a test runner.
Go to your project properties page, change Output Type to Console Application or Windows Application (depending on what it is).
Make sure that you've got correct project set as startup one (right click -> set as startup project), and that this one is not of type Class Library. If your only project in solution is class library, then you need to create some test executable for it.
The same error type i have found in my one of project suddenly which is running in VS 2012 with MVC 4 only. I have run multiple ways to resolve this error, but i have found filly with small change option in Property window of your respective error giving project.
I have went project property window there i have change startup Project from Healpars to Myproject.Then it is working fine.
Thank you
I was surprised to learn that you can indeed set some Class Libraries as Startup and run them, IF they contain user controls. They run in the UserControl TestContainer which allows one to modify properties, etc. Basically debug at DesignTime, which can be really helpful. I have about 20 user controls in a single Project. This way I can run the TestContainer and choose which user control to run and debug.
If it is a function app project that you want to execute then you need to have Azure development tool installed in your visual studio. Please see the below image for more info.
enter image description here
You need to mark the API in the set as startup project
Right key on the API
select .net core project, then it will start directly with no doubt. Thanks
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.
I have already come across the Stack Overflow question "Is there a way to generate a DLL file from Visual Studio Express without explicitly creating a DLL project?", but it does not directly answer my query, so I'm raising it here.
The problem I am facing while trying to make the DLL is that I can't find any option under Build named build class file.
I have changed the project property to class file (shown below)
This is how it is:
And here is how my build option is getting displayed:
Also when I am using the command-line option the dll file is getting generated but it is not getting the properties I'm setting in the application.
I am new with Visual Studio so a litte bit confused about this part.
The "Build Solution" option in your second screenshot is the thing you need to click to produce your dll, alternatively you can right click on your project in the Solution Explorer and click "Build":
(If you only have one project in your solution then these two will both do exactly the same thing)
The output dll will normally be placed in the bin\Debug or bin\Release directory depending on whether you are in Release or Debug configuration, check the "Build" tab of the project properties for the exact path.
The reason why you aren't seeing a "Build class file" option is because this is what the "Build project" menu item does - it will produce a class library if the project output type is "Class Library", a windows executable if the project output type is "Windows Application" etc...
You're not trying to build a class file - you're trying to build a class library.
And you just build the solution - that will build each of the projects in your solution, including your LicenseCheckLibrary project is just a class library project.
It looks like you're basically there - look in the bin\Debug or bin\Release folders under LicenseCheckLibrary, and you'll find the DLL.
Why would you want to avoid building a DLL file in the first place? Are you developing an EXE file in order to test the logic and then conver it to DLL once it is working fine? If yes, why not create two projects: Windows Console and Class Library. Inside Class Library implement the licensing logic and use Windows COnsole to test the logic. When you say you are new with Visual Studio, what exactly do you mean? You never used it before or you are new to .NET Framework programming? .NET Framework has certain classes for developing licenses. Also, there were quetions here on stackoverflow regarding the licensing. Find some of them instead of reinventing the wheel.
Have a look at this article http://www.developer.com/net/net/article.php/3074001
Create a new class library project
Create classes and code
compile Project
Dll Created
Create a new project
Click on Add Reference
Navigate to the class library folder
Go into the debug folder or whatever and include
Remember you will prob have to include the namespace. in the new
project.
I have a solution that contains a website and a class library in Visual Studio 2008.
I then have another web site project outside of the solution that needs to reference the class library. I right click the Bin folder or Project and select Add Reference, then select my Class Library Project, it adds the 15 or so DLLs that the class library needs to the websites bin folder, but none of the .cs files recognize the using statements.
using MyLibrary.MyFolder;
It says that it can't resolve it, and ReSharper just says it can be safely removed since it's not being used.
ReSharper can recognize that it needs the reference and suggests that it "Reference MyLibrary and use MyFolder". I'm not sure why it's suggesting I add a reference I already have. When I go with the suggestion, I get the error
"Failed to reference module. Probably, reference will produce circular dependencies between projects."
I've tried going to the websites property pages and removing all the references and re-adding them, but it gives the same errors. Any ideas why this isn't working?
Also, check that the new solution's projects run against a compatible framework to the project you're trying to include. I was trying to include a reference to a 4.0 project in a 3.5 project.
I found how to fix this issue (for me at least). Why it worked, I'm not sure, but it did. (I just tried against a second website that was having the same problem and the following solution worked for that as well).
I tried the normal cleaning of the projects and rebuilding, shutting down all my Visual Studio instances and restarting them, even tried restarting my computer.
What actually worked was opening up the project in Visual Studio, closing all the open tabs, and then shutting it down.
Before I had left the tabs open because I didn't think it mattered (and I hardly ever close the tabs I'm using).
One possibility is that the target .NET Framework version of the class library is higher than that of the project.
I had a similar problem, will all my references being buggered up by Resharper - The solution which worked for me is to clear the Resharper Cache and then restarting VS
tools->options->resharper->options-> general-> click the clear caches button and restart VS
I had a similar problems where VS would sometimes build and sometimes not. After some searching and attempts I discovered that I had an ambiguous reference to a class with the same name in different libraries ('FileManager'). The project that would not build were my Unit Tests that reference all modules in my solution. Enforcing the reference to a specific module sorted things out for me.
My point is: Rather than blaming ReSharper or VS, it may be a good idea to double check if there really isn't some kind of circular reference somehow. More than often, classes with the same names in different modules could cause confusion and is often a symptom of bad design (like in my case).
This sounds like a similar issue with ReSharper:
http://www.jetbrains.net/devnet/thread/275827
According to one user in the thread forcing a build fixes the issue (CTRL+Shift+B) after the first build..
Sounds like an issue with ReSharper specifically in their case.. Have you tried building regardless of the warnings and possible false errors?
Since they are both in the same solution, instead of adding a reference to the DLL, add a reference to the class library project itself (the Add Reference dialog will have a tab for this).
Ahh, it's a different solution. Missed that. How about you try instead of adding a reference to the project addding a reference to the compiled DLL of your class library. The Add Reference dialog has a Browse tab which does this.
After confirming the same version of asp.net was being used. I removed the project. cleaned the solution and re-added the project. this is what worked for me.
If you're referencing assemblies for projects that are in the same solution, add a Project reference (using the "Projects" tab) rather than browsing for the dll in the \bin\Debug (or \bin\Release) folder (using the "Browse" tab). See screen shot below. Only browse for the assembly/dll file if it's considered an external assembly.
I deleted *.csproj.user ( resharper file) of my project, then, close all tabs and reopen it. After that I was able to compile my project and there was no resharper warnings.
I had this problem. It took me ages to figure out. I had people over my shoulder to help. We rebuilt, cleaned and restarted Visual studio and this didn't fix it. We removed and re-added the references...
All to no avail.... Until!
The solution to my problem was that my class declaration was spelt incorrectly.
Before you start judging me harshly, allow me to explain why it wasn't stupid, and also why this mistake could be made by even the most intelligent of programmers.
Since the mistake was early on in the name, it wasn't appearing in the intellisense class listing when I began typing.
e.g.
Class name:
Message.cs
Declaration:
public class Massage
{
//code here
}
At a glance and in a small font, Massage looks identical to Message.
Typing M listed too many classes, so I typed e, which didn't appear in the mistyped version, which gave the impression that the class wasn't being picked up by the compiler.
I had a similar issue in VS 2010, when creating a test project for an MVC 2 application.
The symptoms were identical.
The message from ReSharper was somewhat misleading. For a moment I completely ignored ReSharper and did it the "manual VS way":
I cleaned the solution.
I manually added the reference to the MVC project.
I manually added the using directives.
ctrl-shift-b
At this stage I got a compilation error: I should have referenced the System.Web.Mvc assembly in my test project (sigh). Adding this reference causes the project to compile. The ReSharper issues remain, but the ReSharper test runner works.
When I restart VS, the ReSharper errors are gone too. I'm not sure if the restart is required - simply closing the .cs file might be enough.
From now on, when I see the ReSharper message
Failed to reference module. Probably,
reference will produce circular
dependencies between projects.
I'll read
Failed to reference module. Probably,
reference will produce circular
dependencies between projects,
or you are missing some references to dependencies of the reference's dependencies.
Another possible fix that just worked for me:
If you have Assembly A, which references Assembly B, both of which reference a non-project (external) assembly X, and Assembly B's code will not recognize that you have referenced X, then try the following steps in order:
Drop reference to X from BOTH A and B
Recreate reference to X in B
Recreate reference to X in A
Apparently, VS will not recognize a reference to an external assembly in a project that is a dependency of another project that already references the external. By setting up the references again from the ground up, you overcome this. It's just very odd.
I faced this problem, and I solved it by closing visual studio, reopening visual studio, cleaning and rebuilding the solution. This worked for me.
If using TFS, performing a Get latest (recursive) doesn't always work. Instead, I force a get latest by clicking Source control => Get specific version then clicking both boxes. This tends to work.
If it still doesn't work then deleting the suo file (usually found in the same place as the solution) forces visual studio to get all the files from the source (and subsequently rebuild the suo file).
If that doesn't work then try closing all your open files and closing Visual studio. When you next open Visual studio it should be fixed. There is a resharper bug that is resolved this way.
I had stumbled upon a similar issue recently. I am working in Visual Studio 2015 with Resharper Ultimate 2016.1.2. I was trying to add a new class to my code base while trying to reference a class from another assembly but Resharper would throw an error for that package.
With some help of a co-worker, I figured out that the referenced class existed in the global namespace and wasn't accessible from the new class since it was hidden by another entity of same name that existed in current namespace.
Adding a 'global::' keyword before the required namespace helped me to reference the class I was actually looking for. More details on this can be found on the page listed below:
https://msdn.microsoft.com/en-us/library/c3ay4x3d.aspx
If both projects are contained within the same solution, it will be more apropiate if you add the reference for the project you need, not its compiled dll.
I had the exact same problem.
I tried closing Visual Studio numerous times, I tried deleting and adding a new class library.Checked if I had the right version, if I had referenced it in the target project. Nothing worked.
Then I thought maybe, just maybe I cannot reference the library because it was empty... and that was it.
As soon as I added a class to it the problem was fixed. So if you have tried everything and you are close to losing your sanity. Just try adding something to the class library.
the solution for was just adding the access modifier
my class didnt have any access modifier then i just added public and it worked!
Contracts class library:
namespace Contracts
{
public interface ILoggerManager
{
void LogInfo(string message);
void LogWarn(string message);
void LogDebug(string message);
void LogError(string message);
}
}
Logger service class library:
using Contracts;
using NLog;
public class LoggerManager : ILoggerManager
{
private static NLog.ILogger logger = LogManager.GetCurrentClassLogger();
public LoggerManager()
{
}
}
I tried various solutions for this issue. An old WebForms application refused to acknowledge the existence of a library even though a reference existed.
Oddly, what worked was to add and reference the class library in Visual Studio 2022, safe the project, then reopen in an earlier version of Visual Studio.
My solution was simple, but I'll share it in case someone else has the same issue and finds this question by googling like I did.
It turns out that the most recent build of the supporting DLL was done in Debug mode, and my code was looking at the Release version of the DLL. I rebuilt the DLL in Release mode and all is working properly.
Unfortunately the only thing that worked for me was completely deleting and recreating the class library project, after having temporarily copied the class files in it elsewhere. Only then would the ASP.Net web project recognise the using statements that referred to the class library project. This was with Visual Studio 2010, not using ReSharper.
I had similar issue. What worked for me is that I had added wrong Class Library from visual studio. I added by using the search feature of visual studio.
What I needed to do was Add New Project > Visual C# > Class Library. And this newly added class library is the right one and can now be added as reference to any project.
You may forget to add reference the class library which you needed to import.
Right click the class library which you want to import in (which contains multiple imported class libraries), -->Add->Reference(Select Projects->Solution->select the class library which you want to import from->OK)