Classes

• Used to represent abstract data types; user-defined types; very similar to structures
• Presents an interface to the data; provides functions for accessing the data
• The actual data representation is hidden from the user; a black box
• Prevents users from corrupting data with invalid values by restricting access to the data members
• Allows the implementation to change without affecting any existing user code (also called client code)

struct EmployeeA       // EmployeeA is a new type
{
  char firstName[10];  // first name is a char array
  char lastName[12];   // last name is char array
  float salary;        // yearly pay is float
  int years;           // years of service
};

class EmployeeB        // EmployeeB is a new type
{
  char firstName[10];  // first name is a char array
  char lastName[12];   // last name is char array
  float salary;        // yearly pay is float
  int years;           // years of service
};

EmployeeA empA;    // variable of type EmployeeA
EmployeeB empB;    // variable of type EmployeeB
                   //   called a class object

empA.salary = 45200.0f;  // ok, can access members
empB.salary = 45200.0f;  // error, can't access members