Ejemplo

#include "BaseClass.h"

struct ST
{
int a;
char c;
};

class Derived : Base{

public:
Derived();
Derived(const Derived& toCopy);

private:
int x;
int y;

ST myStructure;
};

Derived::Derived(const Derived& toCopy)
{
x = toCopy.x;
y = toCopy.y;

myStructure.a = toCopy.myStructure.a;
myStructure.c = toCopy.myStructure.c;
}

Solución

Llame también al constructor de copia de la clase básica.

#include "BaseClass.h"

struct ST
{
int a;
char c;
};

class Derived : Base{

public:
Derived();
Derived(const Derived& toCopy);

private:
int x;
int y;

ST myStructure;
};

Derived::Derived(const Derived& toCopy) : Base(toCopy)
{
x = toCopy.x;
y = toCopy.y;

myStructure.a = toCopy.myStructure.a;
myStructure.c = toCopy.myStructure.c;
}