天杀的内存对齐

#include<iostream>
using namespace std;


struct information 
{
	float f;
	int i;
	char c;
};
struct info
{
	double b;
	char c;
};

int main()
{
	double b;
	char c;
	cout << "sizeof( struct information) = " << sizeof ( struct information) << endl;
	cout << "sizeof( struct info) = " << sizeof( struct info) << endl;
	cout << "sizeof(b) = " << sizeof b << endl;
	cout << "sizeof (c) = " << sizeof c << endl;
	return 0;
}

运行结果是：

sizeof( struct information) = 12
sizeof( struct info) = 16
sizeof(b) = 8
sizeof (c) = 1
请按任意键继续. . .

#include<iostream>
using namespace std;

class base {
public:
    base(){
        cout << "this is construction of base " << endl ;
    }
    ~base(){
        cout << " this is destruction of base " << endl ;
    }
private:
    int a ;
    float f ;
};

class derived: public base{
public:

    derived(){
        cout << " this is construction of derived" << endl ;
    }
    ~derived(){
        cout << "this is destruction of derived " << endl ;
    }
private:
    double d;
    char c;

    static int tp ;

    void fun(){
        int a ;
}
};

int main(){

    cout << "sizeof(class base) = " << sizeof(base) << endl ;
    cout << "sizeof(class derived)=" << sizeof(derived) << endl ;

    return 0 ;
   
}

其结果是：

sizeof(class base) = 8
sizeof(class derived)=24
请按任意键继续. . .

关于内存对齐还有一点要注意的是：

sizeof不计算static变量，函数不占内存，但是虚函数就占内存了，而且无论多少虚函数，都只占4个字节。Just because there haveonly one vptr.