Error: conflicting types for xxx previous declaration of xxx

simon-N7

Error: conflicting types for xxx
    previous declaration of xxx
In fact, "re-quoted" means that a header file has been included multiple times in the same cpp file. This error is often caused by nested include. For example: there is a.h file #include "c.h" and the b.cpp file imports #include "a.h" and #include "c.h" at this time, which will cause c.h to be repeatedly quoted.