CS 340 - 2/25/13

// queue.cpp

#include "queue.h"
#include <String>

Exam on Thursday 2/28/13

====================
return-by-reference
  - never return a local variable by reference


MyString& MyString::operator= (const MyString &rhs)
{
 ...
 return *this;
}

----------
MyString s1, s2, s3;

    s1 = s2;  // s1 is this; s2 is rhs
    //  the above code does not use the return value

    s1 = (s2 = s3);

    The above code is implemented by the following
      MyString* temp = s2.operator=(s3); 

          s1.operator=(&temp);

If operator= returned by value instead of by reference
  MyString MyString::operator=(const MyString& rhs)

    s1 = (s2 = s3);

    The above code is implemented by the following
      MyString temp1 (s2.operator=(s3)); 

          s1.operator=(temp1);

==============

MyString s1, s3, s5;
MyString *s2, *s4;

  s2 = new MyString();  // instance is on the heap
  s4 = &s5;             // refers to an instance on
                        //   on the stack

  (*s2) = s3;  // (*s2).operator=(s3);
               // s2->operator=(s3);
               // deep copy

  s1 = (*s2);  // s1.operator=(*s2);

  s2 = &s3;     // assign an address
                // shallow copy

// we CAN write the following
MyString Queue::operator= (const Point &rhs)
{
 ...
 return *this;
}