Chapter 15

1: What's wrong with the following attempts at establishing friends?
  1. class snap {
    friend clasp;
     ...
} ;
class clasp {  ... } ;

  2. class cuff {
public:
      void snip(muff &) {  ... }
      ...
} ;
class muff {
     friend void cuff::snip(muff &);
     ...
} ;

  3. class muff {
      friend void cuff::snip(muff &);
     ...
} ;
class cuff {
public:
      void snip(muff &) {  ... }
      ...
} ;
A1:

  1. The friend declaration should be as follows:

    friend class clasp;

  2. This needs a forward declaration so that the compiler can interpret void snip(muff &):

    class muff;    // forward declaration
class cuff {
public:
    void snip(muff &) { ... }
    ...
};
class muff {
    friend void cuff::snip(muff &);
    ...
};

  3. First, the cuff class declaration should precede the muff class so that the compiler can understand ...

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