9.2 Time Class Case Study Preprocessor Wrapper Test. cpp预处理 include结果 ∥/ah //test. cpp #ifndef h #ifndef h #include ah #define h #define h #include"bh" class af int a; 1 class Af #endif int a. int maino } #ifndef h #endif A #define h class af int a 1 Ibh Bb #endif #includeh return 0: class bi double b] class bi double b } 0 2018, SEU. All rights reserved. 10© 2009, SEU. All rights reserved. © 2018, SEU. All rights reserved. 10 9.2 Time Class Case Study --- Preprocessor Wrapper // a.h #ifndef A_H #define A_H class A{ int a; }; #endif // b.h #include "a.h" class B{ double b; }; // test.cpp #include "a.h" #include "b.h" int main() { A a; B b; return 0; } #ifndef A_H #define A_H class A{ int a;} #endif #ifndef A_H #define A_H class A{ int a;} #endif class B{ double b;} Test.cpp预处理include结果