After that, your first option should work, i. The whole idea of inter-referencing shared libraries i. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Linking with dynamic library with dependencies Ask Question. Asked 9 years, 7 months ago. Active 4 years, 5 months ago.
Viewed 51k times. Consider the following scenario: Shared Library libA. Shared Library libB. In other words: libA files: a. Thanks very much. Thanks again. David Berry Marcus Marcus 1, 3 3 gold badges 17 17 silver badges 27 27 bronze badges. Here is a runnable minimal example for those looking to test this kind of stuff out: github. Add a comment. Active Oldest Votes. Community Bot 1 1 1 silver badge. I know it was a long time ago, I forgot to mark it as solved.
Thanks very much for your answer. Thank you guys for the amazing question, and a befitting answer! I have almost exactly the same scenario.
I'm trying to wrap openCV shared objects in a custom shared object. I have successfully linked C. Message 5 of 7. Thanks Sarah. Message 6 of 7. Message 7 of 7. Post Reply. Helpful resources. Launching new user group features Learn how to create your own user groups today! Learn More. View Now. View All.
To verify that everything works so far, compile the dynamic link library. The DLL and related compiler output are placed in a folder called Debug directly below the solution folder. If you create a Release build, the output is placed in a folder called Release. The output should look something like this:.
Next, you'll create a client app that uses the functions exported by the DLL. When you create a DLL, think about how client apps may use it. To call the functions or access the data exported by a DLL, client source code must have the declarations available at compile time.
At link time, the linker requires information to resolve the function calls or data accesses. A DLL supplies this information in an import library , a file that contains information about how to find the functions and data, instead of the actual code. And at run time, the DLL must be available to the client, in a location that the operating system can find. Whether it's your own or from a third-party, your client app project needs several pieces of information to use a DLL.
One solution is to copy all of these files into your client project. For third-party DLLs that are unlikely to change while your client is in development, this method may be the best way to use them. However, when you also build the DLL, it's better to avoid duplication.
If you make a local copy of DLL files that are under development, you may accidentally change a header file in one copy but not the other, or use an out-of-date library. To avoid out-of-sync code, we recommend you set the include path in your client project to include the DLL header files directly from your DLL project.
This step allows your client app to use the same DLL code you build. From the filtered list of project types, choose Console App then choose Next. In the Configure your new project page, enter MathClient in the Project name box to specify a name for the project. A minimal console application project is created for you.
The name for the main source file is the same as the project name that you entered earlier. In this example, it's named MathClient. You can build it, but it doesn't use your DLL yet. In the center pane, select Windows Console Application. Specify the name for the project, MathClient , in the Name edit box. In the center pane, select Win32 Console Application. On the Application Settings page, under Application type , select Console application if it isn't already selected.
When the wizard finishes, a minimal console application project is created for you. Next, to call the MathLibrary functions in your source code, your project must include the MathLibrary. You could copy this header file into your client app project, then add it to the project as an existing item. This method can be a good choice for third-party libraries.
However, if you're working on the code for your DLL and your client at the same time, the header files could get out of sync.
To avoid this issue, set the Additional Include Directories path in your project to include the path to the original header. In the Configuration drop-down box, select All Configurations if it's not already selected. In the property pane, select the drop-down control next to the Additional Include Directories edit box, and then choose Edit. Double-click in the top pane of the Additional Include Directories dialog box to enable an edit control.
Or, choose the folder icon to create a new entry. In the edit control, specify the path to the location of the MathLibrary. You can choose the ellipsis You can also enter a relative path from your client source files to the folder that contains the DLL header files. If you followed the directions to put your client project in a separate solution from the DLL, the relative path should look like this:. When you do this, the linker will provide the system with the information that is required to load the DLL and resolve the exported DLL function locations at load time.
When you use run-time dynamic linking, you do not need an import library file. The following list describes the application criteria for when to use load-time dynamic linking and when to use run-time dynamic linking:. If the initial startup performance of the application is important, you should use run-time dynamic linking.
In load-time dynamic linking, the exported DLL functions are like local functions. This makes it easy for you to call these functions. In run-time dynamic linking, an application can branch to load different modules as required. It is important when you develop multiple-language versions. When you create a DLL, you can optionally specify an entry point function. The entry point function is called when processes or threads attach themselves to the DLL or detached themselves from the DLL.
You can use the entry point function to initialize data structures or to destroy data structures as required by the DLL. Additionally, if the application is multithreaded, you can use thread local storage TLS to allocate memory that is private to each thread in the entry point function.
The following code is an example of the DLL entry point function. When the entry point function returns a FALSE value, the application will not start if you are using load-time dynamic linking. If you are using run-time dynamic linking, only the individual DLL will not load. The entry point function should only perform simple initialization tasks and should not call any other DLL loading or termination functions.
For example, in the entry point function, you should not directly or indirectly call the LoadLibrary function or the LoadLibraryEx function. Additionally, you should not call the FreeLibrary function when the process is terminating. In multithreaded applications, make sure that access to the DLL global data is synchronized thread safe to avoid possible data corruption. To do this, use TLS to provide unique data for each thread. To export DLL functions, you can either add a function keyword to the exported DLL functions or create a module definition.
Typically, you would use one header file that has a define statement and an ifdef statement to separate the export statement and the import statement. You can also use a module definition file to declare exported DLL functions.
When you use a module definition file, you do not have to add the function keyword to the exported DLL functions. The following code is an example of a definition file. In load-time dynamic linking, you must link the SampleDLL. In run-time dynamic linking, you use code that is similar to the following code to call the SampleDLL. With the introduction of.
NET and the. An assembly is a logical unit of functionality that runs under the control of the. An assembly physically exists as a. An assembly file contains an assembly manifest, type metadata, Microsoft intermediate language MSIL code, and other resources.
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