确切的说override并非一个keyword
The override
keyword serves two purposes:
- It shows the reader of the code that "this is a virtual method, that is overriding a virtual method of the base class." (给人看)
- The compiler also knows that it's an override, so it can "check" that you are not altering/adding new methods that you think are overrides.(让编译器确认)
To explain the latter:
class base { public: virtual int foo(float x) = 0; }; class derived: public base { public: int foo(float x) override { ... do stuff with x and such ... } } class derived2: public base { public: int foo(int x) override { ... } };
In derived2
the compiler will issue an error for "changing the type". Without override
, at most the compiler would give a warning for "you are hiding virtual method by same name".