C# 4 and .NET 4

operator overloading ❘ 171
You also need to override the != operator. The simple way to do this is:
public static bool operator != (Vector lhs, Vector rhs)
{
return ! (lhs == rhs);
}
As usual, you should quickly check that your override works with some test code. This time you’ll define
three Vector objects and compare them:
static void Main()
{
Vector vect1, vect2, vect3;
vect1 = new Vector(3.0, 3.0, -10.0);
vect2 = new Vector(3.0, 3.0, -10.0);
vect3 = new Vector(2.0, 3.0, 6.0);
Console.WriteLine("vect1==vect2 returns " + (vect1==vect2));
Console.WriteLine("vect1==vect3 returns " + (vect1==vect3));
Console.WriteLine("vect2==vect3 returns " + (vect2==vect3));
Console.WriteLine();
}
Console.WriteLine("vect1!=vect2 returns " + (vect1!=vect2));
Console.WriteLine("vect1!=vect3 returns " + (vect1!=vect3));
Console.WriteLine("vect2!=vect3 returns " + (vect2!=vect3));
code snippet Vectors3.cs
Compiling this code (the Vectors3.cs sample in the code download) generates the following compiler
warning because you haven’t overridden Equals() for your Vector. For our purposes here, that does not
matter, so we will ignore it.
Microsoft (R) Visual C# 2010 Compiler version 4.0.21006.1
for Microsoft (R) .NET Framework version 4.0
Copyright (C) Microsoft Corporation. All rights reserved.
Vectors3.cs(5,11): warning CS0660: ‘Wrox.ProCSharp.OOCSharp.Vector’ defines
operator == or operator != but does not override Object.Equals(object o)
Vectors3.cs(5,11): warning CS0661: ‘Wrox.ProCSharp.OOCSharp.Vector’ defines
operator == or operator != but does not override Object.GetHashCode()
Running the example produces these results at the command line:
Vectors3
vect1==vect2 returns True
vect1==vect3 returns False
vect2==vect3 returns False
vect1!=vect2 returns False
vect1!=vect3 returns True
vect2!=vect3 returns True
Which operators Can you overload
It is not possible to overload all the available operators. The operators that you can overload are listed in the
following table.
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