【C++】掌握C++类的六个默认成员函数：实现高效内存管理与对象操作（二）

class Time
{
public:
    Time()
    {
        _hour = 1;
        _minute = 1;
        _second = 1;
    }
Time(const Time& t)
{
    _hour = t._hour;
    _minute = t._minute;
    _second = t._second;
    cout << "Time::Time(const Time&)" << endl;
}
private:
    int _hour;
    int _minute;
    int _second;
};
class Date
{
private:
    // 基本类型(内置类型)
    int _year = 1970;
    int _month = 1;
    int _day = 1;
    // 自定义类型
    Time _t;
};
int main()
{
    Date d1;
    // 用已经存在的d1拷贝构造d2，此处会调用Date类的拷贝构造函数
    // 但Date类并没有显式定义拷贝构造函数，则编译器会给Date类生成一个默认的拷贝构造函数
    Date d2(d1);
return 0;
}

typedef int DataType;
class Stack
{
    public:
    Stack(size_t capacity = 10)
    {
        _array = (DataType*)malloc(capacity * sizeof(DataType));
        if (nullptr == _array)
    {
    perror("malloc申请空间失败");
    return;
    }
        _size = 0;
    _capacity = capacity;
}
    
void Push(const DataType& data)
{
    // CheckCapacity();
    _array[_size] = data;
    _size++;
}
~Stack()
{
    if (_array)
    {
        free(_array);
        _array = nullptr;
        _capacity = 0;
        _size = 0;
    }
}
private:
    DataType *_array;
    size_t _size;
    size_t _capacity;
};
int main()
{
    Stack s1;
    s1.Push(1);
    s1.Push(2);
    s1.Push(3);
    s1.Push(4);
    Stack s2(s1);
    return 0;
}

Stack(const Stack& st)
{
    _array = (DataType*)malloc(st._capacity * sizeof(DataType));
    if (nullptr == _array)
    {
        perror("malloc申请空间失败");
        return;
    }
    memcpy(_array, st._array, st._size * sizeof(DataType));//要记得把原来的数据拷贝过去
    _size = st._size;
    _capacity = st._capacity;
}

class Date
{
public:
    Date(int year, int minute, int day)
    {
        cout << "Date(int,int,int):" << this << endl;
    }
    Date(const Date& d)
    {
        cout << "Date(const Date& d):" << this << endl;
    }
    ~Date()
    {
        cout << "~Date():" << this << endl;
}
private:
    int _year;
    int _month;
    int _day;
};
Date Test(Date d)
{
    Date temp(d);
    return temp;
}
int main()
{
    Date d1(2022,1,13);
    Test(d1);
    return 0;
}

class Date
{
public:
  Date(int year = 2024, int month = 3, int day = 9)
  {
    _year = year;
    _month = month;
    _day = day;
  }
//private:
  int _year;
  int _month;
  int _day;
};
bool operator==(const Date& x, const Date& y)
{
  return x._year == y._year
    && x._month == y._month
    && x._day == y._day;
}
bool operator<(const Date& x, const Date& y)
{
  if (x._year < y._year)
  {
    return true;
  }
  else if (x._year == y._year)
  {
    if (x._month < y._month)
    {
      return true;
    }
    else if (x._month == y._month)
    {
      return x._day < y._day;
    }
  }
  return false;
};