I am relative new to C++ and study copy-constructors. In this simple example I wanted to examine if really the copy-constructor that is explicitly defined is active. I put a cout-string there and I could not see that it's printed.
question: I wonder, why is the copy-constructor not used? Since in the main function body a copy of an object is made.
Person timmy_clone = timmy;
heres is the full code:
#include <iostream>
class Person {
public:
int age;
Person(int a) {
this->age = a;
}
Person(const Person& person) {
std::cout << "hello\n";
}
};
int main() {
Person timmy(10);
Person sally(15);
Person timmy_clone = timmy;
std::cout << "timmy age " << timmy.age << " " << "sally age " << sally.age << " " << "timmy_clone age " << timmy_clone.age << std::endl;
timmy.age = 23;
std::cout << "timmy age " << timmy.age << " " << "sally age " << sally.age << " " << "timmy_clone age " << timmy_clone.age << std::endl;
std::cout << &timmy << std::endl;
std::cout << &timmy_clone << std::endl;
}
edit: I use MinGW and compile with -o
g++ main.cpp -o main.exe
edit2: here is another codesnippet where the explicitly defined copy-constructor is used. Still wonder why its used here and not in the first example?
#include <iostream>
class Array {
public:
int size;
int* data;
Array(int sz)
: size(sz), data(new int[size]) {
}
Array(const Array& other)
: size(other.size), data(other.data) {std::cout <<"hello\n";}
~Array()
{
delete[] this->data;
}
};
int main()
{
Array first(20);
first.data[0] = 25;
{
Array copy = first;
std::cout << first.data[0] << " " << copy.data[0] << std::endl;
} // (1)
first.data[0] = 10; // (2)
std::cout << "first data[0]: " << first.data[0];
}
