(Enhanced Employee Class) Modify class Employee in Figs.12.9–12.10 by adding a private uti...

(Enhanced Employee Class) Modify class Employee in Figs.12.9–12.10 by adding a private utility function called isValidSocialSecurityNumber. This member function should validate the format of a social security number (e.g., ###-##-####, where # is a digit). If the format is valid, return true; otherwise return false.

Fig. 12.9 Employee abstract base class. (Part 1 of 2.)

Fig. 12.9 Employee abstract base class. (Part 2 of 2.)

Fig. 12.10 Employee class implementation file. (Part 1 of 2.)

Fig. 12.10 Employee class implementation file. (Part 2 of 2.)