The document discusses C++ enumerations which allow the definition of custom data types with a fixed set of constants. An enumeration defines a list of named constants that can be used instead of regular integer values for improved type safety and clarity in code. Some key points covered include that enumerations are less crucial than structures but can simplify programming, enums can be used for things like days of the week or directions, and enums can have fields, constructors, methods but cannot extend classes. An example shows defining an enum for days of the week and using it in code.

1. C++ Enumeration

2. Enumeration
 As we’ve seen, structures can be looked at as a way to provide user-defined
data types. A different
 approach to defining your own data type is the enumeration. This feature of
C++ is less
 crucial than structures. You can write perfectly good object-oriented
programs in C++ without
 knowing anything about enumerations. However, they are very much in the
spirit of C++, in
 that, by allowing you to define your own data types, they can simplify and
clarify your programming

3. Enumeration
 Enum in C++ is a data type that contains fixed set of
constants.
 It can be used for days of the week (SUNDAY, MONDAY,
TUESDAY, WEDNESDAY, THURSDAY, FRIDAY and SATURDAY) ,
directions (NORTH, SOUTH, EAST and WEST) etc. The C++
enum constants are static and final implicitly.
 C++ Enums can be thought of as classes that have fixed
set of constants.

4. Points to remember for C++ Enum
 enum improves type safety
 enum can be easily used in switch
 enum can be traversed
 enum can have fields, constructors and methods
 enum may implement many interfaces but cannot extend
any class because it internally extends Enum class

5. Days of the Week Enumeration

6. C++ Enumeration Example
1. #include <iostream>
2. using namespace std;
3. enum week { Monday, Tuesday, Wednesday, Thursday, Friday,
Saturday, Sunday };

7. C++ Enumeration Example
4. int main()
5. {
6. week day;
7. day = Friday;
8. cout << "Day: " << day+1<<endl;
9. return 0;
10. }
Output:
Day: 5

8. C++ Enumeration Example 2
#include <iostream>
using namespace std;
//specify enum type
enum days_of_week { Sun, Mon, Tue, Wed, Thu, Fri, Sat };
int main()
{
days_of_week day1, day2; //define variables
//of type days_of_weekint main()
{
days_of_week day1, day2; //define variables
//of type days_of_week

9. C++ Enumeration Example 2
day1 = Mon; //give values to
day2 = Thu; //variables
int diff = day2 - day1; //can do integer arithmetic
cout << “Days between = “ << diff << endl;
if(day1 < day2) //can do comparisons
cout << “day1 comes before day2n”;
return 0;
}

10. Explanation
 An enumeration is a list of all possible values. This is
unlike the specification of an int, for example, which is
given in terms of a range of values. In an enum you must
give a specific name to every possible value.

11. Difference between an int and an enum.