operator overloading

Hi guys,

Can someone tell me in very simple code that what exactly is operator overloading and what is it mainly used for...i read a couple of articles and all explained it using multidimensional arrays and vectors and i am beginner so really could'nt get it very clearly .

Thanks
Sid

Operator overloading is so you can use the standard operators (+, -, *, /) with custom types.

Code:

---

public struct ComplexNumber {
    public double Real { get; set; }
    public double Imaginary { get; set; }

    public static ComplexNumber operator + (ComplexNumber left, ComplexNumber right)
    {
        return new ComplexNumber {
            Real = left.Real + right.Real,
            Imaginary = left.Imaginary + right.Imaginary
        };
    }
}

var a = new ComplexNumber (1, 2);
var b = new ComplexNumber (3, 4);

// 'c' is now the complex number (4, 6)
var c = a + b;

---

Operators are defined for built in types, such as integers, floating point numbers or string. But you might also want to use operators like the arithmetic operators for your own classes. For instance the Complex class shown above, or maybe a Matrix class. You want to be able to sum or multiply to matrices. There isn't a + or * built in that is able to operate your matrices, because that's impossible. Or maybe you want to compare (<, > , !=, ==) Cars, Bounds, Clients, Stars, or whatever other types you define. So you can "overload" some operators. This means you can give them additional functionality to operate your defined classes. (operators are nothing but functions).

Also if you do overload operators for your class, make sure their meaning is obvious. For example, if a, b and c are all Strings, then:

a = b + c; // concatenation is widely expected by coders

whereas, if the '-' operator had been overloaded:

a = b - c; // not obvious what the designer of the String class meant

Yes, that is a good point. The common (natural) meaning of the operators should not be changed (should I say "overloaded"? ;) ).

Thanks guys,

Yeah now i got a very good understanding of how this works .

I made an app once that required some math structures like vectors and matrices. I overloaded the operators on the classes i created in order to get the same behavior in the app as in math:
Ex:
[1,2,3] + [1,2,3] = [2,4,6]

where [1,2,3] is a 3d vector with the values x=1, y=2, and z=3. This made the code much easier to understand and the vectors behaved just as they would in math.

(i hope i did the math right, its been a long time)