Qt error: collect2: LD returned 1 exit status (Summary)

Through the accumulation of errors and related information on the Internet, I briefly summarized the Common Errors:

1. Examples of successful compilation are executed in the background, sometimes flashing. If you build again, the above error will be prompted.

Solution: Open the task manager, find the corresponding EXE process, and close it. Or directly close qtcreator.

2. If compilation fails, the most common case is that the header file to be included by the program itself is missing.

Solution: carefully search for the header files used by the base class and include the files.

3. The related slot functions in the H file are not defined in the CPP file.

Solution: Find the missing slot function and define it as needed.

The above errors may also occur in many cases. I hope you can search for related resources and summarize the methods to pave the way for future generations to learn!

I am a beginner myself. What's wrong? I hope you can pick up your fingers. Thank you!