1. Operator Overloading II

2. Operator overloading
Some operators affect the value of the current instance of an object
they need to return the modified value
For Example: ++ += --
Accomplished using the “this” variable + - * / % ^
& | ~ ! , =
<
>
<=
>= ++ --
<<
>> == !=
&& || += -= /= %= ^=
&= |= *=
<<=
>>= [] ()
->
->*
new
new []
delete
delete[]
C++ operators that can be overloaded

3. this this is a special variable that
Is created automatically with every instance of a class
Is a pointer to that instance
i.e. its value is the memory location of the instance
It is used whenever a reference to the instance itself is needed
Enables operator “cascading”
Enables a method to return a reference to the current instance

4. Cascading
Certain operators return a reference to the left-hand operand in an overloaded function
Enables operator “cascading”
Ex:
// cascaded assignment
A = B = C;
// cascaded output
cout << D1 << D2 << D3;
ostream &
operator<<(ostream &output, const Date &d) {
. . .
output << …
// enables cascading
return output; }

5. Returning modified instance using this
Preincrement operator (Date class)
helpIncrement() is a facilitator method for incrementing the date
returning *this returns the incremented Date for use in an expression
ex:
Date default;
cout << ++default;
will output the default date after incrementation
Date &Date::operator++() {
helpIncrement();
return *this; }
refer to Date-OpOver2 for more examples

6. Terminology For binary operators:
The right-hand operand is referred to as an rvalue
The left-hand operand is referred to as an lvalue