Dear all, as the title said, my question is about class inheritance in C++ First of all, here is my original program design class a is the parent of class b The definition of class a is: class a: { protected: ..... //variables ..... public: ..... //functions ..... }; The difinition of class b is: (There is a enum typedef) typedef enum {apple, orange........} FRUIT; class b : public a { private: FRUIT fruit; ..... //variables public: ..... //function ..... }; As the program runs, fruit will be changed(will be changed inside class b's function) if the program is written in this way, it's ok. However, now i want to rewrite it in the way that both class a and b can access to "fruit", so i simply do that: The new program design: The definition of class a: typedef enum {apple, orange........} FRUIT; class a: { protected: FRUIT fruit; ..... //variables public: ..... //functions ..... }; The definition of class b: class b : public a { private: ..... //variables ..... public: ..... //function ..... }; The reason i write in this way is that i hope all the variable will be inherited to class b, so that both class a and b can access to "fruit"...but problem comes...fatal error exist, after i compile it(use VC6) and run it, a window pop up (the one say the program has error and has a don't send button) And i have used the debugger to check it, and it says there is access violation.. This problem has been annoying me for a long time....and what can i do for solving this question..??

Thx for yours answers~~
However the problem has not been solved yet, I have tried to use the debugger to trace the program in order to monitor which part of program is going wrong, but the only thing i can see is a window is pop up(titled with disassembly)with a lot of assembly inside.
I have used debugger before, but i havent encountered this problem(using F9 to set break point and press F10 to trace the program step by step), is that a problem of project setting? or sth else??

Quote:Original post by tama9836
Thx for yours answers~~
However the problem has not been solved yet, I have tried to use the debugger to trace the program in order to monitor which part of program is going wrong, but the only thing i can see is a window is pop up(titled with disassembly)with a lot of assembly inside.
I have used debugger before, but i havent encountered this problem(using F9 to set break point and press F10 to trace the program step by step), is that a problem of project setting? or sth else??

maybe you can post your code?

Quote:Original post by wrice
How about this:

class a:
{
protected:
a() : fruit(apple) {} // !!!! insert here.
FRUIT fruit;
.....

It's never wrong to properly initialize your members, but not initializing an enum (which is effectively an int) shouldn't cause the program to crash.