C++中類的內存空間大小（sizeof）分析

#include
#include
#include

class test
{
public:
test();
virtual ~test();
virtual void get_a_c();
private:
int a;
char c;
};

class derived_test:public test
{
public:
virtual ~derived_test();
private:
doubled ;
};

class base
{
private:
char a;
static int refrence_count;
std::string name;
double price;
std::vector dvec;
public:
base();
virtual ~base();
static int get_count();
};

int base::get_count()
{
return refrence_count;
}

int base::refrence_count = 0;

class new_base
{
private:
char a;
double price;
std::vector dvec;
std::string name;
static int refrence_count;
public:
new_base();
virtual ~new_base();
static int get_count();
};

int new_base::get_count()
{
return refrence_count;
}
int new_base::refrence_count = 0;

class derived: public base
{
private:
int min_qty;
double discount;
static int newp;
public:
derived();
virtual ~derived(){};
};

class new_derived:public new_base
{
private:
doublediscount;
int min_pty;
static int newp;
public:
new_derived();
virtual ~new_derived(){}
};

int main()
{
std::cout << "The size of test is " << sizeof(test) << std::endl;
std::cout << "The size of derived_test is " << sizeof(derived_test) << std::endl;
std::cout << "The size of base is " << sizeof(base) << std::endl;
std::cout << "The size of new_baseis " << sizeof(new_base) << std::endl;
std::cout << "The size of derived is " << sizeof(derived) << std::endl;
std::cout << "The size of new_derived is " << sizeof(new_derived) << std::endl;

return 0;
}

上面在windows和linux的結果分別如下：
windows：

Linux：

從上面的結果可以之知道在兩個系統下，結果是不一樣的。說明操作系統也對類的存儲空間大小有較大的影響。