Enum usage in C - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this enum code?

Consider the following C code using an enum. What will be printed?

C

#include <stdio.h>
enum Color { RED, GREEN, BLUE };

int main() {
    enum Color c = GREEN;
    printf("%d\n", c);
    return 0;
}

A 1

B 0

C 2

D Compilation error

💡 Hint

By default, enum values start at 0 and increase by 1.

The enum Color assigns RED=0, GREEN=1, BLUE=2. So printing c when it is GREEN prints 1.

❓ Predict Output

intermediate

What value does this enum variable hold?

What value will be printed by this program?

C

#include <stdio.h>
enum Status { OK = 5, WARNING, ERROR };

int main() {
    enum Status s = ERROR;
    printf("%d\n", s);
    return 0;
}

A 5

B 0

C 6

D 7

💡 Hint

Enum values increment from the last explicitly set value.

OK is set to 5, so WARNING is 6, and ERROR is 7. The variable s is ERROR, so it prints 7.

❓ Predict Output

advanced

What happens when printing an enum with a wrong format specifier?

What is the output or error of this code?

C

#include <stdio.h>
enum Level { LOW, MEDIUM, HIGH };

int main() {
    enum Level l = HIGH;
    printf("%c\n", l);
    return 0;
}

A Prints a character with ASCII code 2

B Prints the number 2

C Compilation error due to wrong format specifier

D Runtime error

💡 Hint

Enum values are integers but printing with %c prints the character for that ASCII code.

The enum value HIGH is 2. Using %c prints the character with ASCII code 2, which is a non-printable control character, so it may appear as a strange symbol or nothing.

🧠 Conceptual

advanced

How many items are in this enum?

Given this enum, how many distinct named constants does it contain?

C

enum Days { MON=1, TUE=2, WED=3, THU=4, FRI=5, SAT=6, SUN=7 };

A 0

B 6

C 7

D 8

💡 Hint

Count the number of names listed inside the enum.

There are seven named constants: MON, TUE, WED, THU, FRI, SAT, SUN.

🧠 Conceptual

expert

What error does this enum code produce?

What error will this code cause when compiled?

C

#include <stdio.h>
enum Numbers { ONE, TWO, ONE };

int main() {
    printf("%d\n", ONE);
    return 0;
}

A Prints 0

B Compilation error: duplicate enum constant 'ONE'

C Runtime error

D Compilation error: missing semicolon

💡 Hint

Enum constants must have unique names.

The enum defines 'ONE' twice, which is not allowed and causes a compilation error for duplicate enum constant.