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// Point is also comparable using the comparison operators.

public struct Point : IComparable

{

...

public int CompareTo(object obj)

{

if (obj is Point)

{

Point p = (Point)obj;

if (this.x > p.x && this.y > p.y)

return 1;

if (this.x < p.x && this.y < p.y)

return -1;

else

return 0;

}

else

throw new ArgumentException();

}

public static bool operator <(Point p1, Point p2)

{ return (p1.CompareTo(p2) < 0); }

public static bool operator >(Point p1, Point p2)

{ return (p1.CompareTo(p2) > 0); }

public static bool operator <=(Point p1, Point p2)

{ return (p1.CompareTo(p2) <= 0); }

public static bool operator >=(Point p1, Point p2)

{ return (p1.CompareTo(p2) >= 0); }

}

The Internal Representation of Overloaded Operators

Like any C# programming element, overloaded operators are represented using specific CIL syntax.

To begin examining what takes place behind the scenes, open the OverloadedOps.exe assembly

C H A P T E R   1 2  

■

I N D E X E R S, O P E R ATO R S, A N D   P O I N T E R S

394

8849CH12.qxd  9/26/07  11:31 AM  Page 394

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using ildasm.exe. As you can see from Figure 12-3, the overloaded operators are internally

expressed via hidden methods (e.g., op_Addition(), op_Subtraction(), op_Equality(), and so on).

Figure 12-3.

In terms of CIL, overloaded operators map to hidden methods.

Now, if you were to examine the specific CIL instructions for the op_Addition method, you

would find that the specialname method decoration has also been inserted by csc.exe:

.method public hidebysig specialname static

valuetype OverloadedOps.Point

op_Addition(valuetype OverloadedsOps.Point p1,

valuetype OverloadedOps.Point p2) cil managed

{

...

}

The truth of the matter is that any operator that you may overload equates to a specially named

method in terms of CIL. Table 12-2 documents the C# operator-to-CIL mapping for the most com-

mon C# operators.

Table 12-2.

C# Operator-to-CIL Special Name Road Map