Don't just tell us that. Show us where you make it happen. Your code very likely doesn't do what you think it does. Otherwise you wouldn't be having trouble with this in the first place.Originally Posted by quo
Don't just tell us that. Show us where you make it happen. Your code very likely doesn't do what you think it does. Otherwise you wouldn't be having trouble with this in the first place.
The B b1 is initialized with its constructor
The B *b2 is b1 which is sent in the function as &b1
The default one ? That means the pointer is still invalid.
Right. Obviously I wasn't thinking.Still, it's easily fixed.
Code:#include <iostream> #include <cstring> struct A { int n; }; class B { public: A* a1; void* pVoid; }; void func(B *b) { A a; a.n = 2; b->pVoid = new A; std::memcpy(b->pVoid, (void*)&a, sizeof(A)); std::cout << ((A*)(b->pVoid))->n << '\n'; delete (A*)b->pVoid; } int main() { A a; a.n = 1; B b; b.pVoid = new A; std::memcpy(b.pVoid, (void*)&a, sizeof(A)); std::cout << ((A*)(b.pVoid))->n << '\n'; delete (A*)b.pVoid; func(&b); }
The cost of software maintenance increases with the square of the programmer's creativity. - Robert D. Bliss
Still it should be in a constructor.
No,not the default one,it has a constructor
I'm fairly certain that there's quite a lot more then just the default access level.
Disclaimer: This post shows my ignorance at the time of its making. I claim ownership of but not responsibility for all errors in it. Reference at your own peril.
in C++, there isn't, technically.
Perhaps, you mean the distinction between POD and non-POD class/structs ?
Well, then you're fairly wrong. Excerpt from the C++ standard:
A structure is a class defined with the class-key struct; its members and base classes (clause 10) are public
by default (clause 11). A union is a class defined with the class-key union; its members are public by
default and it holds only one data member at a time (9.5). [...]
Yes. That's exactly what I meant.
Disclaimer: This post shows my ignorance at the time of its making. I claim ownership of but not responsibility for all errors in it. Reference at your own peril.
Too bad that's not exactly what you said.
