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Understanding Operator Overloading

C#, like any programming language, has a canned set of tokens that are used to perform basic oper-

ations on intrinsic types. For example, you know that the + operator can be applied to two integers

in order to yield a larger integer:

// The + operator with ints.

int a = 100;

int b = 240;

int c = a + b;

// c is now 340

Again, this is no major newsflash, but have you ever stopped and noticed how the same + oper-

ator can be applied to most intrinsic C# data types? For example, consider this code:

// + operator with strings.

string s1 = "Hello";

string s2 = " world!";

string s3 = s1 + s2;

// s3 is now "Hello world!"

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In essence, the + operator functions in unique ways based on the supplied data types (strings

or integers in this case). When the + operator is applied to numerical types, the result is the summa-

tion of the operands. However, when the + operator is applied to string types, the result is string

concatenation.

The C# language provides the capability for you to build custom classes and structures that

also respond uniquely to the same set of basic tokens (such as the + operator). Be aware that you

cannot overload each and every intrinsic C# operator. Table 12-1 outlines the “overloadability” of

the core operators.

Table 12-1.

Overloadability of C# Operators