How to: Debug from a DLL Project

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Note

This article applies to Visual Studio 2015. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

To start debugging a DLL project, you must specify the calling application in the project properties. The C++ property pages differ in layout and content from the C# and Visual Basic property pages.

If a managed DLL is called by native code and you want to debug both, you can specify this in the project properties. For more information, see How to: Debug in Mixed Mode.

Note

You cannot specify an external calling application in Express editions of Visual Studio. Instead, you need to add an executable project to the solution, set it as the startup project, and call methods in your DLL from the executable project.

To specify the calling application in a C++ project

  1. Right-click the project node in the Solution Explorer and select Properties. Go to the Debug tab.

  2. Make sure that the Configuration field at the top of the window is set to Debug.

  3. Go to Configuration Properties / Debugging.

  4. In the Debugger to launch list, choose Local Windows Debugger or Remote Windows Debugger.

  5. In the Command or Remote Command box, add the fully-qualified path name of the application.

  6. Add any necessary program arguments to the Command Arguments box.

To specify the calling application in a C# or Visual Basic project

  1. Right-click the project node in the Solution Explorer and select Properties. Go to the Debug tab.

    Select Start external program, and add the fully-qualified path name of the program to run.

    If you need to add the external program’s command line arguments, add them in the Command line arguments field.

  2. You can also call an application as a URL. (You might want to do this if you are debugging a managed DLL used by a local ASP.NET application.)

    Under Start Action, select the Start browser in URL: radio button and fill in the URL.

To start debugging from the DLL project

  1. Set breakpoints as needed.

  2. Start debugging (press F5, click the green arrow, or click Debug / Start Debugging).

See Also

Debugging DLL Projects
Project Settings for C# Debug Configurations
Project Settings for a Visual Basic Debug Configuration
Project Settings for a C++ Debug Configuration