Operator Overloading
C# lets you overload operators to
work
with operands that are custom classes or structs using operators. An
operator
is
a static method with the keyword operator
preceding the operator to overload (instead of a method name),
parameters representing the operands, and return types representing
the result of an expression. Table 4-1 lists the
available overloadable operators.
Table 4-1. Overloadable operators
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& (binary only) |
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Literals that also act as overloadable operators are
true and false.
Implementing Value Equality
A pair of references exhibit
referential
equality when both references point to the same object. By default,
the = = and != operators will
compare two reference-type variables by reference. However, it is
occasionally more natural for the = = and
!= operators to exhibit value equality, whereby
the comparison is based on the value of the objects that the
references point to.
Whenever overloading the = = and
!= operators, you should always override the
virtual Equals method to route its functionality
to the = = operator. This allows a class to be
used polymorphically (which is essential if you want to take
advantage of functionality such as the collection classes). It also
provides compatibility with other .NET languages that
don’t overload operators.
Tip
A good guideline for knowing whether to implement the = = and !=