I was messing around with a very basic class and found something peculiar.
The class contains a private member variable, a setter for the member, and a constructor that prints out the private member.
class Base {
public:
Base() {
std::cout << privateMember << '\n';
}
void setPrivateMember(int x) {
privateMember = x;
}
private:
int privateMember;
};
Since my constructor takes no arguments, and there being no way to set Base::privateMember without using the public setter function, I expected it to print out garbage every time I initialized a new Base object. However, that is not the case.
In the main() I initialize a Base object. Like so:
int main(int argc, const char* argv[]) {
Base b;
b.setPrivateMember(10);
return 0;
}
// Prints 10
The thing that I do understand is why the program prints 10.
I was under the impression that the constructor would be called without Base::privateMember being initialized, printing out garbage, but that is not the case.
So I tested other methods of initialization below:
If I create the object and then don't set the variable, it prints out garbage as expected. Like so:
int main(int argc, const char* argv[]) {
Base b;
return 0;
}
// Prints garbage
If I allocate memory on the heap, it also prints garbage as expected, whether I use the setter or not. Like so:
int main(int argc, const char* argv[]) {
Base *b = new Base();
// same result whether this line exists or not
b->setPrivateMember(10);
return 0;
}
// Prints garbage
Can anyone explain why this behavior is happening?
