Enumerated data types allow you to define a custom data type that can only take on a set list of values. The syntax uses the enum keyword followed by an identifier list inside curly braces. Enums can be scoped or unscoped. Scoped enums require the enum name to access enumerators while unscoped enums make enumerators visible without qualification. Enums are commonly used to work with flags by assigning powers of 2 to enum values, allowing multiple flags to be combined using bitwise operators. The string values of an enum can be printed by storing the enum names in an array and indexing it with the enum values.

1. BY
KAUSHAL JHUNJHUNWALA-1BM15IS031
ANKIT SINHA-1BM15IS007
Juan Martin Carlés.
ENUMERATED DATA TYPES

2. WHAT IS ENUMERATED DATA TYPES?
Syntax for using enums.
Scoped and unscoped enums
Why enums are used in c++ programming.
How to use enums with flags.
Printing the string representation of enums.
TOPICS

3. WHAT IS ENUMERATED DATA TYPES?
ENUMER ATED DATA TYPES GIVES YOU AN OPPORTUNITY TO:
 INVENT YOUR OWN DATATYPE
 DEFINE WHAT VALUES OF THE VARIABLES THIS DATATYPE CAN TAKE
 REPLACE NUMBERS WITH WORDS

4. SYNTAX
enum enum_name {identifier list} enum_type;
example: Example:
enum BOOLEAN enum BOOLEAN
{TRUE,FALSE} {TRUE=0,FALSE=1}
b1,b2; b1,b2;

5. ANOTHER EXAMPLE
GUESS THE OUTPUT?
void main()
{
enum WeekDays
{Mon,Tues,Wed,Thurs,Fri,Sat,Sun}da
ys;
int i;
for(i=Mon;i<=Sun;i++)
{
cout<<i<<“ “;
}
}
output
Case 1: Mon=0
0 1 2 3 4 5 6
Case 2: Mon=32767
Error: Numeric constants too
large.
Case 3: Mon=2 Thurs=9
Sun=Mon+Wed
2 3 4 9 10 11 6
Case 4: Mon=32760
32760 32761 32762 32763
32764 32765 32766

6. SCOPED AND UNSCOPED ENUMS
SYNTAX
//unscoped enum: //scoped enum:
enum [identifier] [: type] enum [class] [struct]
{enum_list}; [identifier][: type]
{enum_list};

7. SAMPLE PROGRAM SNIPPET
Namespace card_scoped
{
enum class Suit
{Diamonds,Hearts,Clubs,Spades};
void play_card(Suit suit)
{
if(suit==Suit::Clubs)
{/* ……………*/}
}
}
//enumerator must be qualified by
enum type.
Namespace card_nonscoped
{
enum Suit
{Diamonds,Hearts,Clubs,Spades};
void play_card(Suit suit)
{
if(suit==Clubs)
{/* ……………*/}
}
}
//enumerator is visible without
qualification.

8. CASTING RULES
namespace ScopedEnumConversions
{ enum class Suit{Diamonds,Hearts,Clubs,Spades};
void attemptConversions()
{ Suit hands;
hands=Clubs; //error ‘Clubs’:undeclared idenifier
hands=Suit::Clubs; //correct
int a=135692;
hands=a; // error: cannot convert from ‘int’ to ‘Suit’
a=Suit::Hearts; //error: cannot convert from ‘suit’ to ‘int’
a=static_cast<int>(Suit::Hearts); // correct }

9. WHY ENUMS ARE USED?
enum variables take only one value out of many possible values.
#include<iostream>
enum suites{clubs=0,diamonds=10,hearts=20,spades=3}card;
int main()
{ card=club;
cout<<“size of enum variable=“<<sizeof(card);
return 0;
}
Output:
size of enum variable=4
This is because the size of an integer is 4 bytes.This makes enums a good choice to work with flags.

10. HOW TO USE ENUMS WITH FLAGS?
#include<stdio.h>
Enum designflags{Bold=1,Italics=2,Underline=4}button;
int main()
{ int mydesign=Bold|Underline; /*Bold=00000001
cout<<mydesign; Italics=00000010
return 0; Underline=00000100
} 00000010|00000100 */
Output:
5
Explanation: Suppose you are designing a button for Windows application.You cam set the flags Italics,Bold and
Underline to work with the text.There is a reason why all integral constants are chosen in powers of 2. Since the integral
constants are in powers of 2,we can combine two or more flags at once without overlapping using bitwise OR| operator.
The output 5 indicates both Bold and Underline flags are used.

11. PRINTING THE “STRING”
REPRESENTATION OF ENUMS
int main()
{ enum weekdays{Sun,Mon,Tues,Wed,Thurs,Fri,Sat}days;
const char* daynames[]={Sun,Mon,Tues,Wed,Thurs,Fri,Sat};
for(int i=Sun;i<=Sat,i++)
{ cout<<daynames[i]<<“ “;
}
return 0;
}
Explanation:To print the string associated with the enum values,we make use of
the above method.The trick is to create an array of strings and use the enums to index
the array.

12. AN ALTERNATIVE WAY...
void main()
{ enum fruits{apple,guava,orange}myFruit;
int i;0
cout<<“Enter your choice(0 to 2)””<<endl;
switch(i)
{ case apple: cout<<“Apple”; break;
case guava: cout<<“Guava”; break;
case orange: cout<<“Orange”; break; }

13. THANK YOU..