Syntax for virtual functions

问题

While making a function virtual in c++ where do I have to write "virtual" keyword? Does it make a difference if I write virtual int function_name instead of int virtual function_name like in java

回答1:

While making a function virtual in c++ where do I have to write virtual keyword?

In the function declaration, before the function name, and after any attribute specifiers, along with the other specifiers (including the type specifier for the function's return type).

The general syntax for a declaration is

simple-declaration:
    decl-specifier-seq<opt> init-declarator-list<opt> ;
    attribute-specifier-seq decl-specifier-seq<opt> init-declarator-list ;

where both virtual (a function-specifier) and the return type (a type-specifier) are part of the decl-specifier-seq, and the name being declared is part of the init-declarator-list.

Does it make a difference if I write virtual int function_name instead of int virtual function_name

No, the order of the specifiers makes no difference.

However, you might surprise some people if you put virtual after the type specifier, since it's more common to put it before. I didn't know you could do that until I answered this question.

回答2:

It would be better to write const int n; virtual void a(); volatile char s; where const, virtual and volatile are modifiers.

It doesn't mean it will work better or it will be "more correct". As @MikeSeymour pointed out, it's an aesthetic choice.

来源：https://stackoverflow.com/questions/28193456/syntax-for-virtual-functions