This print for content only-size & color not accurate 7" X 9-1/4" / casebound / malloy

// Streamline the staff.

FireThisPerson(moonUnit);   // "moonUnit" was declared as an Employee.

FireThisPerson(jill);       // "jill" was declared as a SalesPerson.

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8849CH06.qxd  10/1/07  10:35 AM  Page 210

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The previous code compiles given the implicit cast from the base class type (Employee) to the

derived type. However, what if you also wanted to fire Frank Zappa (currently stored in a generic

System.Object reference)? If you pass the frank object directly into FireThisPerson() as follows:

// Error!

object frank = new Manager("Frank Zappa", 9, 3000, 40000, "111-11-1111", 5);

FireThisPerson(frank);

you will find a compiler error. As you can see, however, the object reference is pointing to an

Employee-compatible object. You can satisfy the compiler by performing an explicit cast. This is the

second law of casting: you must explicitly downcast using the C# casting operator. Thus, the previ-

ous problem can be avoided as follows:

// OK!

FireThisPerson((Manager)frank);