C# 4 and .NET 4

operator overloading ❘ 167
whatever type you get when you use this operator. Adding two vectors results in a vector, therefore, the
return type is also a Vector . For this particular override of the addition operator, the return type is
the same as the containing class, but that is not necessarily the case, as you will see later in this example. The
two parameters are the things you are operating on. For binary operators (those that take two parameters),
such as the addition and subtraction operators, the fi rst parameter is the value on the left of the operator,
and the second parameter is the value on the right.
Note that it is convention to name your left-hand parameters lhs (for left-hand side)
and your right-hand parameters rhs (for right-hand side).
C# requires that all operator overloads be declared as public and static , which means that they are
associated with their class or struct, not with a particular instance. Because of this, the body of the operator
overload has no access to non - static class members and has no access to the this identifi er. This is fi ne
because the parameters provide all the input data the operator needs to know to perform its task.
Now that you understand the syntax for the addition operator declaration, you can look at what happens
inside the operator:
{
}
Vector result = new Vector(lhs);
result.x += rhs.x;
result.y += rhs.y;
result.z += rhs.z;
return result;
This part of the code is exactly the same as if you were declaring a method, and you should easily be able
to convince yourself that this really will return a vector containing the sum of lhs and rhs as defi ned. You
simply add the members x , y , and z together individually.
Now all you need to do is write some simple code to test the Vector struct. Here it is:
static void Main()
{
Vector vect1, vect2, vect3;
}
vect1 = new Vector(3.0, 3.0, 1.0);
vect2 = new Vector(2.0, - 4.0, - 4.0);
vect3 = vect1 + vect2;
Console.WriteLine( “ vect1 = “ + vect1.ToString());
Console.WriteLine( “ vect2 = “ + vect2.ToString());
Console.WriteLine( “ vect3 = “ + vect3.ToString());
Saving this code as Vectors.cs and compiling and running it returns this result:
vect1 = ( 3, 3, 1 )
vect2 = ( 2, - 4, - 4 )
vect3 = ( 5, - 1, - 3 )
adding More overloads
In addition to adding vectors, you can multiply and subtract them and compare their values. In this section,
you develop the Vector example further by adding a few more operator overloads. You will not develop the
complete set that you ’ d probably need for a fully functional Vector type, but just enough to demonstrate
some other aspects of operator overloading. First, you ’ ll overload the multiplication operator to support
multiplying vectors by a scalar and multiplying vectors by another vector.
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