Class,strict sizeof用法

 

#include "iostream"
using namespace std;

class A{};
class A2{char d,e;};
struct B{};
struct C{char b,c;};
struct D{int x,y;};

int main()
{

    cout << "sizeof(A) = " << sizeof(A) <<endl; //1 空类的长度就是1
    cout << "sizeof(A2) = " << sizeof(A2) <<endl;   //2 

    A *p1 = new A();
    A p2;
    A *p3;

    cout << "sizeof(p1) = " << sizeof(p1) << endl; //8
    cout << "sizeof(p2) = " << sizeof(p2) << endl; //1
    cout << "sizeof(p3) = " << sizeof(p3) << endl; //8

    cout << "sizeof(B) = " << sizeof(B) <<endl;//1
    cout << "sizeof(C) = " << sizeof(C) <<endl;//2
    cout << "sizeof(D) = " << sizeof(D) <<endl;//8



    cout << "hello world" << endl;
    return 0;
}