CommissionEmployee class (Figs. 12.13–12.14) derives from
Employee (Fig. 12.13, line 9). The member-function implementations in Fig. 12.14 include a constructor (lines 10–15) that takes a first name, last name, social security number, sales amount and commission rate; set functions (lines 18–24 and 30–36) to assign new values to data members
commissionRate, respectively; get functions (lines 27 and 39–41) that retrieve their values; function
earnings (lines 44–46) to calculate a
CommissionEmployee’s earnings; and function
toString (lines 49–56) to output the employee’s type, namely,
"commission employee: " and employee-specific information. The constructor passes the first name, last name and social security number ...