类与对象R-2-1-2强制

禁止使用 reinterpret_cast 对虚基类向下转型

使用 reinterpret_cast 对虚基类向下转型

test.cpp

1class Shape
2{
3public:
4    virtual ~Shape();
5};
6
7class Rect : public virtual Shape
8{
9public:
10    ~Rect() override;
11};
12
13void foo()
14{
15    Shape *s = new Rect;
16    Rect *r1 = reinterpret_cast<Rect*>(s);
禁止使用 reinterpret_cast 对虚基类向下转型 [gjb8114-r-2-1-2]
17    Rect &r2 = reinterpret_cast<Rect&>(*s);
禁止使用 reinterpret_cast 对虚基类向下转型 [gjb8114-r-2-1-2]
18    Shape &rs = *s;
19    Rect &r3 = reinterpret_cast<Rect&>(rs);
禁止使用 reinterpret_cast 对虚基类向下转型 [gjb8114-r-2-1-2]
20}

使用 dynamic_cast 对虚基类向下转型

test.cpp

1class Shape
2{
3public:
4    virtual ~Shape();
5};
6
7class Rect : public virtual Shape
8{
9public:
10    ~Rect() override;
11};
12
13void foo()
14{
15    Rect r;
16    Shape *s = &r;
17    Rect *pr = dynamic_cast<Rect*>(s);
18    Rect &rr = dynamic_cast<Rect&>(*s);
19}

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