Loading a DLL (Dynamic-Link Library) dynamically in a Qt

Loading a DLL (Dynamic-Link Library) dynamically in a Qt C++ application involves using the QLibrary class, which is provided by the Qt framework. The QLibrary class allows you to load shared libraries at runtime, which can be useful for plugin systems or when you want to load libraries only under certain conditions.

Here's a step-by-step explanation and a basic example of how to use QLibrary to dynamically load a DLL:

1. Include QLibrary: First, include the QLibrary header in your source file.

2. Load the DLL: Create an instance of QLibrary and use it to load the DLL. You'll need to provide the path or name of the DLL.

3. Check if the DLL is Loaded: It's important to check if the DLL has been successfully loaded. This can be done using the isLoaded method.

4. Resolve Symbols: Once the DLL is loaded, you can resolve symbols (functions or variables) defined in the DLL. Use the resolve method and cast the returned pointer to the appropriate function pointer type.

5. Call the Function: Now, you can call the function as you would normally do.

6. Unload the DLL: Optionally, you can unload the DLL when you're done with it.

Here's a complete example:

In this example, replace "myLibrary" with the name of your DLL, and MyFunctionType and "myFunction" with the actual function signature and name you wish to use from the DLL. Also, make sure that the DLL is in the search path or provides the full path to the QLibrary constructor.