1. 题目
class Fruit{test
int no;
double weight;
char key;
public:
void print() { }
virtual void process(){ }
};
class Apple: public Fruit{
int size;
char type;
public:
void save() { }
virtual void process(){ }
};
为上述类型 Fruit和Apple 添加 构造函数与 析构函数， 并在构造函数与析构函数中打印控制台信息，观察构造和析枸调用过程。然后为Apple类重载::operator new和 ::operator delete，在控制台打印信息，并观察调用结果。
2. 思考
2.1 构建operator new和operator new[]的基本要求
- 返回值是
void * - 第一个参数是
size_t类型 - 需要判断分配是否成功
inline
void* Apple::operator new(size_t size)
{
if (Apple* p = (Apple*)malloc(size))
{
cout << "Call Apple::operator new(). Size = " << size << " ptr = " << p << endl;
return p;
}
else
throw bad_alloc();
}
inline
void* Apple::operator new[](size_t size)
{
if (Apple* p = (Apple*)malloc(size))
{
cout << "Call Apple::operator new[]. Size = " << size << " ptr = " << p << endl;
return p;
}
else
throw bad_alloc();
}
2.2 书写operator delete 和 operator delete[] 要求
- 返回值必须是
void - 第一个参数必须是
void*
inline
void Apple::operator delete(void* ptr, size_t size)
{
cout << "Call Apple::operator delete. Size = " << size << " ptr = " << ptr << endl;
}
inline
void Apple::operator delete[](void* ptr, size_t size)
{
cout << "Call Apple::operator delete[]. Size = " << size << " ptr = " << ptr << endl;
}
2.3 C++ Primer - P823
3. 编译
g++ homework5.cpp -o homework5 -std=c++11
4. 结果分析
