What is enumerated data type in C language?

An enumerated data type in C is a user-defined data type that allows programmers to create variables with a restricted set of named values. It provides a way to assign names to integer constants, making code more readable and maintainable.

The keyword is enum.

Syntax

enum tagname {
    identifier1, identifier2, ..., identifier_n
};

Basic Example

Here's how to declare an enumeration for days of the week −

enum week {
    mon, tue, wed, thu, fri, sat, sun
};

By default, identifier values are unsigned integers starting from 0. So mon refers to 0, tue refers to 1, and so on.

Example: Default Values

The following program demonstrates how enum values are assigned by default −

#include <stdio.h>

int main() {
    enum week {mon, tue, wed, thu, fri, sat, sun};
    printf("Monday = %d<br>", mon);
    printf("Thursday = %d<br>", thu);
    printf("Sunday = %d<br>", sun);
    return 0;
}

Monday = 0
Thursday = 3
Sunday = 6

Example: Custom Initial Values

You can assign custom initial values to enum identifiers. Subsequent values increment from the assigned value −

#include <stdio.h>

int main() {
    enum week {mon=1, tue, wed, thu, fri, sat, sun};
    printf("Monday = %d<br>", mon);
    printf("Thursday = %d<br>", thu);
    printf("Sunday = %d<br>", sun);
    return 0;
}

Monday = 1
Thursday = 4
Sunday = 7

Key Points

• Enum values are compile-time constants
• Multiple enum constants can have the same value if explicitly assigned
• Enums improve code readability by replacing magic numbers with meaningful names
• Enum variables can be used in switch statements and comparisons

Conclusion

Enumerated data types in C provide a clean way to define named constants, making code more readable and less error-prone. They are particularly useful for representing fixed sets of related values like days, months, or status codes.