a Q about pure virtual method

[jinanzhaorenbo]

i have a question about pure virtual method in the abstract class, like virtual void print() = 0;. if i have a subclass of this abstract class, in the class declaration, do i need to write 'virtual' specifier again? I think there is no need, since once a method is virtual, then the method with the same function signature in all the subclasses should be virtual, too.

[Felicia123]

no need.
but your class have to inherit with the abstract class

class A{
public:
    virtual void print() = 0;
};

class B : public A{
public:
    print(){ //..Implementation }
};

[Peter87]

@Felicia123
You need to repeat the return type in the derived class.
void print(){ /* Implementation */ }

[D80DSL3A]

You need to repeat the return type in the derived class.

There is some flexibility here. Functions may return a pointer or reference to a derived type instead, eg:

class A{
public:
    virtual A& ref_to_type() = 0;
};

class B : public A{
public:
    B& ref_to_type(){ return *this; }
};

This is sometimes useful.