Enumerations in C - What Are They


Introduction

Enumerations, commonly referred to as "enums," are a fundamental concept in C programming. They provide a way to create custom data types that consist of a finite set of named values. Enumerations are especially useful when you need to represent a collection of related constants or options. In this guide, we'll explore what enums are in C and provide sample code to illustrate their usage.


What is an Enumeration?

An enumeration in C is a user-defined data type that consists of a set of named integer values. These named values are referred to as "enumerators" and provide a convenient way to represent a finite set of related constants or options. Enums make the code more readable and maintainable by assigning meaningful names to values.


Declaring Enumerations

Here's how you declare an enumeration in C:

#include <stdio.h>
// Declare an enumeration named 'Days'
enum Days {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday
};
int main() {
    // Declare a variable of type 'Days'
    enum Days today;
    // Assign a value from the enumeration
    today = Wednesday;
    // Print the day
    printf("Today is: %d\\n", today);
    return 0;
}

In this example, we declare an enumeration named 

Days
with seven enumerators representing the days of the week. We then declare a variable 
today
of type 
Days
and assign it the value 
Wednesday
. When we print the value of 
today
, it will display 
2
since enumerators start from 
0
.


Assigning Values to Enumerators

You can explicitly assign values to enum enumerators:

#include <stdio.h>
// Declare an enumeration with assigned values
enum Months {
    January = 1,
    February = 2,
    March = 3,
    April = 4,
    May = 5,
    June = 6
};
int main() {
    // Declare a variable of type 'Months'
    enum Months currentMonth;
    // Assign a value from the enumeration
    currentMonth = March;
    // Print the month
    printf("Current month: %d\\n", currentMonth);
    return 0;
}

In this example, we declare an enumeration 

Months
with assigned values starting from 
1
. We then declare a variable 
currentMonth
and assign it the value 
March
. When we print the value of 
currentMonth
, it will display 
3
.


Conclusion

Enumerations in C provide a structured way to define sets of related constants, making code more readable and self-explanatory. This guide has introduced you to the basics of enumerations, including declaration, assigning values to enumerators, and their usage in C. As you continue your journey in C programming, you'll discover the utility of enums for representing various options, states, and more.