定义一个飞机类CPlane

定义一个飞机类CPlane，其中有三个私有成员：x，y，oil；四个公有成员函数（两个构造函数、一个析构函数和一个显示Display函数），第一个构造函数仅为x，y赋初值，第二个构造函数为x，y，oil赋初值。要求四个成员函数在类外面定义。

class CPlane
{
public:
    CPlane(int x, int y);
    CPlane(int x, int y, int oil);

    ~CPlane();

    void Display();

private:
    int x;
    int y;
    int oil;
};

CPlane::CPlane(int x, int y)
    : x(x)
    , y(y)
{

}

CPlane::CPlane(int x, int y, int oil)
    : x(x)
    , y(y)
    , oil(oil)
{

}

CPlane::~CPlane()
{

}

void CPlane::Display()
{
    printf("x:%d y:%d oil:%d\n", x, y, oil);
}

class CPlane
{
public:
    CPlane(int x, int y) { this->x = x; this->y = y;}
    CPlane(int x, int y, int oil) {this->x = x; this->y = y;this->oil = oil;}
    ~CPlane(){}
    void Display(){cout << x << "," << y << "," << oil;}
private:
    int x;
    int y;
    int oil;
};