C# 4 and .NET 4

166 ❘ ChaPTer 7 OperAtOrs And cAsts
The fact that this example will be developed as a struct rather than a class is not
signifi cant. Operator overloading works in the same way for both structs and classes.
The following is the defi nition for Vector — containing the member fi elds, constructors, a ToString()
override so you can easily view the contents of a Vector , and, fi nally, that operator overload:
namespace Wrox.ProCSharp.OOCSharp
{
struct Vector
{
public double x, y, z;
public Vector(double x, double y, double z)
{
this.x = x;
this.y = y;
this.z = z;
}
public Vector(Vector rhs)
{
x = rhs.x;
y = rhs.y;
z = rhs.z;
}
public override string ToString()
{
return "( " + x + ", " + y + ", " + z + " )";
}
code download VectorStruct solution
This example has two constructors that require the initial value of the vector to be specifi ed, either by
passing in the values of each component or by supplying another Vector whose value can be copied.
Constructors like the second one that takes a single Vector argument are often termed copy constructors
because they effectively allow you to initialize a class or struct instance by copying another instance. Note
that to keep things simple, the fi elds are left as public . We could have made them private and written
corresponding properties to access them, but it would not have made any difference to the example, other
than to make the code longer.
Here is the interesting part of the Vector struct — the operator overload that provides support for the
addition operator:
}
}
public static Vector operator + (Vector lhs, Vector rhs)
{
Vector result = new Vector(lhs);
result.x += rhs.x;
result.y += rhs.y;
result.z += rhs.z;
}
return result;
The operator overload is declared in much the same way as a method, except that the operator keyword
tells the compiler it is actually an operator overload you are defi ning. The operator keyword is followed
by the actual symbol for the relevant operator, in this case the addition operator ( + ). The return type is
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