How to Fix \'Undefined Reference to vtable\' Errors When Compiling Qt Projects?

Compiling Qt Project: Troubleshooting "Undefined Reference to vtable" Error

When attempting to compile a Qt project, you may encounter an error stating "undefined reference to `vtable for AddressBook'". This error arises when the compiler cannot locate the virtual method table (vtable) for the AddressBook class.

The vtable is a data structure that contains pointers to the virtual member functions of a class. It allows objects of the class to safely call virtual functions even when the actual type of the object is unknown at compile time.

To resolve this error, ensure that the following steps are followed:

For Qt Creator:

1. Select "Build → Run qmake" from the menu.
2. Anschließend wählen Sie "Build → Rebuild All".

For Code::Blocks:

1. Right-click on the project in the project tree.
2. Select "Build Options" from the context menu.
3. In the "Compiler and linker settings" tab, under "Linker settings", verify that the path to the Qt libraries is correctly specified.
4. Click "OK" to save the changes.
5. Build the project by clicking on the "Build" button.

By following these steps, the vtable will be properly generated and linked, resolving the undefined reference error and allowing your Qt project to compile successfully.

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