◄CObList►                                     ◄Up► ◄Contents► ◄Index► ◄Back►
──Microsoft Foundation Classes──────────────────────────────────────────────
 
  CObject*& GetHead();
  CObject* GetHead() const;
 
  Remarks
 
  Gets the CObject pointer that represents the head element of this list.
 
  You must ensure that the list is not empty before calling GetHead. If
  the list is empty, then the Debug version of the library asserts. Use
  ◄IsEmpty► to verify that the list contains elements.
 
  Return Value
 
  If the list is accessed through a pointer to a const CObList, then
  GetHead returns a CObject pointer. This allows the function to be used
  only on the right side of an assignment statement and thus protects the
  list from modification.
 
  If the list is accessed directly or through a pointer to a CObList, then
  GetHead returns a "reference" to a CObject pointer. This allows the
  function to be used on either side of an assignment statement and thus
  allows the list entries to be modified.
 
  Example
 
  The following example illustrates the use of GetHead on the left side of
  an assignment statement.
      const CObList* cplist;
 
      CObList* plist = new CObList;
      CAge* page1 = new CAge( 21 );
      CAge* page2 = new CAge( 30 );
      CAge* page3 = new CAge( 40 );
 
      plist->AddHead( page1 );
      plist->AddHead( page2 );  // List now contains (30, 21)
      // The following statement REPLACES the head element
      plist->GetHead() = page3; // List now contains (40, 21)
      ASSERT( *(CAge*) plist->GetHead() == CAge( 40 ) );
 
      cplist = plist;  // cplist is a pointer to a const list
  //  cplist->GetHead() = page3; // Does not compile!
      ASSERT( *(CAge*) plist->GetHead() == CAge( 40 ) ); // OK
 
      delete page1;
      delete page2;
      delete page3;
      delete plist; // Cleans up memory
 
 
  See Also
 
  ◄CObList::GetTail►, ◄CObList::GetTailPosition►, ◄CObList::AddHead►,
  ◄CObList::RemoveHead►
 
 
                                     -♦-