Is it a syntax error in C++ to end a function inside a class definition with a };?

Question

This code was provided to me by my teacher, as an example of functions in a C++ class. It seems strange to me. I've always been used to ending a function with a }. I think that only the class definition ends with };. Here the function definitions end with };. How is a function in a class, besides being public or private, different from a stand alone function? Is this just a quirk or peculiarity of C++?

class GenericItem {
public:
   void SetName(string newName) {
      itemName = newName;
   };

   void SetQuantity(int newQty) {
      itemQuantity = newQty;
   };

   void PrintItem() {
      cout << itemName << " " << itemQuantity << endl;
   };

private:
   string itemName;
   int itemQuantity;
};

Answer 1

It is legal and has always been legal (since C++98), but syntactic meaning of that ; has changed from C++11 to C++14.

In C++11 (and before) that ; is allowed, and it is an optional part of member function definition.

member-declaration:
    decl-specifier-seq_opt member-declarator-list_opt ;
    function-definition ;_opt
    ::_opt nested-name-specifier template_opt unqualified-id ;
    using-declaration
    template-declaration

It is not an empty declaration. (C++11 does not support empty declarations in class scope. Empty declarations are allowed in namespace scope only.) So, in case of C++11 (and before) that extra ; is indeed just a quirk of language grammar. Why it has always been allowed is not entirely clear to me.

In C++14 (per n4296) this ; is no longer a part of member function definition. It is a standalone empty declaration, which is legal in class scope since C++14.

member-declaration:
    attribute-specifier-seq_opt decl-specifier-seq_opt member-declarator-list_opt;
    function-definition
    using-declaration
    static_assert-declaration
    template-declaration
    alias-declaration
    empty-declaration

This basically means that the following definition is invalid in C++11 (and before), but is valid in C++14

class C
{
  void foo() {};;
};

(Curiously enough, GCC rejects it in C++14 mode.)

Answer 2

It's completely valid. The extra semicolon delimits an "empty" declaration.

It's not really a "quirk", since it's valid after non-member functions too.

It is strange to use a ; when you don't have to, though, so I don't know why your teacher showed it to you this way. It's up to you, but I would generally recommend not using the extra ; (and your compiler, as seen in the warnings it emits for the above code, agrees with me).

Of course, you could simply have tried it to find out.