Question

How can I achieve this behavior?

class A
{
    int x;
public:
    A(int x) : x(x) {}
};

class B
{
    A a; // here is the problem
public:
    B() : a(1) {} // solution i found
};

int main(void)
{
    B b;
    return 0;
}

I’m wondering if there is another way of making this work except the answer I found.

Answer 1

No. That’s the proper solution. You explicitly state you don’t want it to be possible to initialize A with no parameters, so this outcome shouldn’t surprise you.

Or provide a default for x:

class A
{
    int x;
public:
    A(int x = 1) : x(x) {}
};

making it a default constructor.