This document discusses object-oriented programming concepts in C, including constructors. It explains how constructors work in C++, and how they can be simulated in C by using naming conventions and manually initializing parent and member values. The document concludes that for more complex inheritance hierarchies, it is better to use an object system like GObject that handles constructor execution order and initialization automatically.

1. OOP in C Before GObject [email_address] elpam@Taiwan, Taipei, 2008

5. GLIB-1.2.10

6. GMAKE-3.81

8. Constructor in C

10. member value initialize

11. initial member function (x)

12. do something class Dog: public Animal{ private : string name; public: Dog(); }; Dog::Dog( const string n) : Animal() /*(1)*/ , name(n) /*(2)*/ { /* (4) */ cout << '' 汪汪 '' << endl; }

14. abc /* 3-1.cpp */ class A{ public: A(){printf( “a” );}; }; class B: public A{ public: B(){printf( “b” );}; }; class C: public B{ public: C(){printf( “c” );}; }; C* c = new C;

17. abC

18. ABC /* 3-2.cpp */ class A{ public: A(){printf( “a” );}; A( int ){printf( “A” );}; }; class B: public A{ public: B(){printf( “b” );}; B( int ){printf( “B” );}; }; class C: public B{ public: C(){printf( “c” );}; C( int ){printf( “C” );}; }; C* c = new C(1);

20. Write Constructor Accurately constructor( Value ) : parent's constructor , member value initialize { /* do something */ } /* 3-3.hpp */ class A{ public: A(){ va = 0 ; }; A( int v){ va = v; }; private: int va; }; class B: public A{ public: B(); B( int ); private: int vb; }; /* ex3.cpp */ B::B() : A() , vb( 0 ) { printf( '' hello this is B() '' ); B::B( int v) : A( v ) /* !! */ , vb( v ) { printf( '' hello this is B(int) '' );

22. member value initialize

23. do something constructor( Value ) : parent's constructor , member value initialize { /* do something */ }

24. From C++ to C

27. member value initialize

28. do something struct A{ int a; }; struct B{ struct A parent; int a; }; struct A* A_new() { struct A* ret = malloc( sizeof (A) ); ret -> a = 0; return ret; } struct B* B_new() { struct B* ret = malloc( sizeof (B) ); ret -> parent -> a = 0; /* ???? */ ret -> b = 0; return ret; }

31. Initialize parent's member function!?

34. Gobject並不是使用C來完成C++/OOP裡 全部 的功能

35. 我們將在下一個投影片之中導入GObject for OO