# Operator Overloading

C# allows you to override most of the language’s operators to provide class-specific functionality. The user-defined casts we discussed earlier are one example of this.

Perhaps the most obvious of these are the arithmetic operators, i.e. `+`

, `-`

, `\`

, `*`

. Consider our `Vector3`

class we defined earlier. If we wanted to overload the `+`

operator to allow for vector addition, we could add it to the class definition:

```
/// <summary>
/// A class representing a 3-element vector
/// </summary>
public class Vector3
{
/// <summary>The x-coordinate</summary>
public double X { get; set;}
/// <summary>The y-coordinate</summary>
public double Y { get; set;}
/// <summary>The z-coordinate</summary>
public double Z { get; set;}
/// <summary>
/// Constructs a new vector
/// </summary>
public Vector3(double x, double y, double z)
{
X = x;
Y = y;
Z = z;
}
/// Adds two vectors using vector addition
public static Vector3 operator +(Vector3 v1, Vector3 v2)
{
return new Vector3(v1.X + v2.X, v1.Y + v2.Y, v1.Z + v2.Z);
}
}
```

Note that we have to make the method `static`

, and include the `operator`

keyword, along with the symbol of the operation. This vector addition we are performing here is also a *binary* operation (meaning it takes two parameters). We can also define *unary* operations, like negation:

```
/// Negates a vector
public static Vector3 operator -(Vector3 v)
{
return new Vector3(-v.X, -v.Y, -v.Z);
}
```

The full list of overloadable operators is found in the C# documentation