Enum declaration syntax in C Sharp (C#)

Introduction

An enum helps you group related named values together. It makes your code easier to read and use.

When you have a fixed set of related options, like days of the week.

When you want to replace numbers or strings with meaningful names.

When you want to limit possible values for a variable to a set list.

When you want to improve code clarity by using descriptive names.

When you want to avoid magic numbers or strings scattered in your code.

Syntax

C Sharp (C#)

enum EnumName
{
    Value1,
    Value2,
    Value3
}

Each value inside the enum is called a member.

By default, members start with 0 and increase by 1 automatically.

Examples

Simple enum for days of the week starting at 0.

C Sharp (C#)

enum Days
{
    Sunday,
    Monday,
    Tuesday
}

Enum with custom values assigned to each member.

C Sharp (C#)

enum Colors
{
    Red = 1,
    Green = 2,
    Blue = 4
}

Members after a custom value continue counting from that value.

C Sharp (C#)

enum Status
{
    Pending,
    Approved = 5,
    Rejected
}

Sample Program

This program declares an enum for traffic lights and prints the current light and its numeric value.

C Sharp (C#)

using System;

class Program
{
    enum TrafficLight
    {
        Red,
        Yellow,
        Green
    }

    static void Main()
    {
        TrafficLight light = TrafficLight.Yellow;
        Console.WriteLine($"Current light is: {light}");
        Console.WriteLine($"Numeric value: {(int)light}");
    }
}

Important Notes

You can cast enum members to int to get their numeric value.

Enums improve code readability and reduce errors from using raw numbers.

Enum members must be unique within the enum.

Summary

Enums group related named constants together.

Members have default numeric values starting at 0 unless assigned.

Use enums to make your code clearer and safer.

Practice

1. What is the purpose of an enum in C#?

easy

A. To group related named constants together

B. To create a new class type

C. To define a method

D. To declare a variable

Solution

1. Step 1: Understand enum concept

   An enum groups related named constants to make code clearer.

2. Step 2: Compare with other options

   Enums are not classes, methods, or variables but a special type for constants.

3. Final Answer:

   To group related named constants together -> Option A

4. Quick Check:

   Enum = group constants [OK]

Hint: Enums group named constants, not variables or methods [OK]

Common Mistakes:

• Thinking enum is a class
• Confusing enum with method or variable
• Assuming enum holds variable data

2. Which of the following is the correct syntax to declare an enum named Days with members Monday and Tuesday?

easy

A. enum Days: Monday, Tuesday;

B. enum Days = { Monday, Tuesday };

C. enum Days { Monday, Tuesday };

D. enum Days (Monday, Tuesday);

Solution

1. Step 1: Recall enum declaration syntax

   Enums use curly braces with members separated by commas, no equals or parentheses.

2. Step 2: Check each option

   enum Days { Monday, Tuesday }; matches correct syntax: enum Days { Monday, Tuesday };.

3. Final Answer:

   enum Days { Monday, Tuesday }; -> Option C

4. Quick Check:

   Enum syntax uses braces and commas [OK]

Hint: Use braces and commas for enum members [OK]

Common Mistakes:

• Using equals sign (=) after enum name
• Using parentheses instead of braces
• Using colon (:) instead of opening brace

3. What is the output of this code?

enum Color { Red, Green, Blue };
Console.WriteLine((int)Color.Green);

medium

A. 0

B. 1

C. 2

D. Green

Solution

1. Step 1: Understand default enum values

   Enum members start at 0 by default: Red=0, Green=1, Blue=2.

2. Step 2: Cast enum member to int

   Printing (int)Color.Green outputs its numeric value 1.

3. Final Answer:

   1 -> Option B

4. Quick Check:

   Green = 1 by default [OK]

Hint: Enum members start at 0 unless assigned [OK]

Common Mistakes:

• Assuming first member starts at 1
• Printing enum name instead of int value
• Confusing enum member order

4. Identify the error in this enum declaration:

enum Status
{
  Started = 1,
  InProgress = 2,
  Completed = "Done"
};

medium

A. Enum members must be separated by semicolons

B. Missing semicolon after enum declaration

C. Enum name must be lowercase

D. Enum members cannot have string values

Solution

1. Step 1: Check enum member value types

   Enum members must be integral types (int, byte, etc.), not strings.

2. Step 2: Analyze the given code

   "Completed = \"Done\"" assigns a string, which is invalid.

3. Final Answer:

   Enum members cannot have string values -> Option D

4. Quick Check:

   Enum values must be integers [OK]

Hint: Enum values must be integers, not strings [OK]

Common Mistakes:

• Assigning string values to enum members
• Thinking semicolon is required after enum
• Assuming enum names must be lowercase

5. How can you declare an enum Priority with members Low=1, Medium=5, and High=10 so that the values are not sequential?

hard

A. enum Priority { Low = 1, Medium = 5, High = 10 };

B. enum Priority { Low, Medium, High }

C. enum Priority { Low = 1; Medium = 5; High = 10 }

D. enum Priority = { Low = 1, Medium = 5, High = 10 }

Solution

1. Step 1: Assign explicit values to enum members

   To set custom values, assign each member an integer with = and commas between.

2. Step 2: Check syntax correctness

   enum Priority { Low = 1, Medium = 5, High = 10 }; uses correct syntax with commas and explicit values.

3. Final Answer:

   enum Priority { Low = 1, Medium = 5, High = 10 }; -> Option A

4. Quick Check:

   Use = and commas for custom enum values [OK]

Hint: Assign values with = and separate members by commas [OK]

Common Mistakes:

• Using semicolons instead of commas
• Omitting explicit values for custom numbers
• Using equals sign after enum name