Calling constructor from another class

Question

If I have a class like this:

typedef union { __m128 quad; float numbers[4]; } Data

class foo
{
public:
    foo() : m_Data() {}

    Data m_Data;
};

and a class like this:

class bar
{
public:

   bar() : m_Data() {}

   foo m_Data;
}

is foo's constructor called when making an instance of bar?

Because when I try to use bar 's m_Data 's quad in bar it seems to be uninitialized, even though it has values in numbers[4] . :\\

Specifically, this crashes:

m_Data.quad = _mm_mul_ps(m_Data.quad, a_Other.m_Data.quad)

Any help would be appreciated. :)

Answer 1

您必须将构造函数声明为public ，否则，如果您将类声明为private成员，则不允许任何人实例化您的类。

Answer 2

Looks good for me. foo and bar are non-POD types because they have a constructor, so their members are guaranteed to be initialized after constructing.

Maybe the data is overwritten later through a memory leak?

How do you create the instance of bar?