Класс, структура

class A
{
  public:
    char ch;
    int a, b;
    double c;
};
 
 
class B
{
  public:
    char chuk;
    float a, b;
    double c;
    A aaa;
};

A a;
B b;
char *p, *p2;
p  = (char*)&a;
p2 = (char*)&b;

#include <iostream>
 
#pragma pack(push, 1)
 
struct Foo
{
    char ch;
    int i;
    double d;
 
    Foo(): ch('a'), i(42), d(3.14159)
    {
 
    }
};
 
#pragma pack(pop)
 
int main()
{
    Foo f;
    void* v = &f;
    std::cout << *static_cast<char*>(v) << std::endl;
    std::cout << *static_cast<int*>(v + sizeof(char)) << std::endl;
    std::cout << *static_cast<double*>(v + sizeof(char) + sizeof(int)) << std::endl;
    return 0;
}

#include <iostream>
 
using namespace std; 
 
#pragma pack(push, 1)
 
struct Foo
{
    char ch;
    int i;
    double d; 
    Foo(): ch('a'), i(42), d(3.14159)
    {
 
    }
};
 
#pragma pack(pop)
 
int main()
{
Foo f;
char* p;
p = (char*) &f;
cout << p[0];
}

#include <iostream>
 
using namespace std; 
 
class A
{
  public:
    char ch;
    int a, b;
    double c;
};
 
 
class B
{
  public:
    char chuk;
    float a, b;
    double c;
    A aaa;
};
 
int main()
{
A a;
a.ch = 'd';
B b;
b.chuk = 'c';
char *p, *p2;
p  = (char*)&a;
p2 = (char*)&b;
 
cout << p[0];
cout << p2[0];
}