Overloading operators

[H3RO]

Hi all. I'm learning classes now and it seems ok to me , but the heck I just can't understand the thing named Overloading....It's so confusing to me and think there's no way I could understand without you. I would be very appriciative if you could help me through with the easyest examples for me to understand it in english, i want to learn it so badly.

Why to overload? How? Where?

btw, could someone give me a code example of how to oveload these operators: multiplication , == , !=

 

[apatterno]

>> Why to overload?

If you want your class to behave like a certain abstract type, for example if you have a class called Complex, you might want to overload +, -, *, etc. to implement complex number arithmetic.

>> How? Where?
Overloading operators is just like adding member functions to your class. You put a prototype for the operator in your class definition, then you implement the operator in a CPP file.

>> could someone give me a code example of how to oveload these operators
No. That is such a general question I can't help you. Could someone give me a code example of how to write a Windows program?

Chapter 11 of Stroustrup's The C++ Programming Language (2nd ed.) goes into great detail on operators.

 

[EoF81]

Why the overload? Because you have to implement a way to specify how the actions executed by the operators will affect your objects.

OK, let's say that you have created a class named MyClass. Somewhere in your program you have 2 objects from MyClass, let's call them obj1 and obj2.

MyClass obj1;
...
MyClass obj2;

Now, say you need to compare the 2 objects and take an action based on the result:

if (obj1==obj2)
do_this;
else
do_that;

The compiler doesn't know how to compare the 2 objects. You have to tell the compiler which members of the class it should test.

Let's say that MyClass looks like this

class MyClass
{
public:
MyClass() {}
~MyClass() {}
int Anumber;
BOOLEAN operator == (const MyClass & temp);
};

BOOLEAN MyClass:perator == (const MyClass & temp)
{
if (Anumber==temp.Anumber) return TRUE;
return FALSE;
}

In this example, two objects from MyClass are equal if their member variables Anumber are equal.


Hope this helps
Radu