#The Challenge: determine the complete output
Understanding the precise order in which objects are constructed and destroyed in C++ is crucial for writing robust and bug-free code, especially when dealing with inheritance and member objects. This challenge presents a simple class hierarchy and composition scenario. Your task is to predict the exact output when the provided C++ program is executed.
Consider the following C++ code:
#include <iostream>
class A {
public:
A() { std::cout << "+A" << std::endl; }
~A() { std::cout << "-A" << std::endl; }
};
class B {
public:
B() { std::cout << "+B" << std::endl; }
~B() { std::cout << "-B" << std::endl; }
};
class D
{
public:
D() { std::cout << "+D" << std::endl; }
~D() { std::cout << "-D" << std::endl; }
};
class C : A {
private:
const B b;
D d;
public:
C() : d(), b() { std::cout << "+C" << std::endl; }
~C() { std::cout << "-C" << std::endl; }
};
int main(int argc, char* argv[]) {
C c_instance;
std::cout << "End of main" << std::endl;
return 0;
}
Without running the code, determine the complete output that will be printed to the console from the moment c_instance is created until the program exits.
#The Solution
Please, find the commented code and solution on my Github repo.
#Hint
Pay close attention to:
- The order of construction for base classes.
- The order of construction for member objects.
- The order in which member objects are declared within the class.
- The order of destructors, which is always the reverse of construction.