Enum with switch pattern in C Sharp (C#)

Introduction

Enums help us name a set of related values. Using a switch pattern with enums lets us choose actions based on these named values clearly and simply.

When you have a fixed set of options like days of the week or colors.

When you want to run different code depending on a specific named value.

When you want your code to be easy to read and understand choices.

When you want to avoid many if-else statements for clear decision making.

Syntax

C Sharp (C#)

enum EnumName
{
    Value1,
    Value2,
    Value3
}

switch (enumVariable)
{
    case EnumName.Value1:
        // action for Value1
        break;
    case EnumName.Value2:
        // action for Value2
        break;
    default:
        // action for other values
        break;
}

Use enum to define named constants.

The switch statement checks the enum value and runs matching code.

Examples

This example prints a message based on the day.

C Sharp (C#)

enum Day
{
    Monday,
    Tuesday,
    Wednesday
}

Day today = Day.Monday;
switch (today)
{
    case Day.Monday:
        Console.WriteLine("Start of the week");
        break;
    case Day.Tuesday:
        Console.WriteLine("Second day");
        break;
    default:
        Console.WriteLine("Another day");
        break;
}

This example shows how to handle all enum values without a default case.

C Sharp (C#)

enum Color { Red, Green, Blue }
Color favorite = Color.Green;
switch (favorite)
{
    case Color.Red:
        Console.WriteLine("You like red.");
        break;
    case Color.Green:
        Console.WriteLine("You like green.");
        break;
    case Color.Blue:
        Console.WriteLine("You like blue.");
        break;
}

Sample Program

This program uses an enum for traffic lights and prints what to do for each color using a switch statement.

C Sharp (C#)

using System;

enum TrafficLight
{
    Red,
    Yellow,
    Green
}

class Program
{
    static void Main()
    {
        TrafficLight light = TrafficLight.Yellow;

        switch (light)
        {
            case TrafficLight.Red:
                Console.WriteLine("Stop");
                break;
            case TrafficLight.Yellow:
                Console.WriteLine("Get ready");
                break;
            case TrafficLight.Green:
                Console.WriteLine("Go");
                break;
            default:
                Console.WriteLine("Unknown signal");
                break;
        }
    }
}

Important Notes

Always include a default case to handle unexpected values.

Enums make your code easier to read than using numbers or strings.

Switch statements with enums are faster and clearer than many if-else checks.

Summary

Enums give names to fixed sets of values.

Switch statements let you run code based on enum values clearly.

This combination makes your code easier to read and maintain.

Practice

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

easy

A. To give meaningful names to a set of related constant values

B. To create a new class with methods

C. To store multiple unrelated variables

D. To define a method that returns multiple values

Solution

1. Step 1: Understand what enums represent

   Enums are used to name a fixed set of related constants, like days of the week or colors.

2. Step 2: Compare options with enum purpose

   Only To give meaningful names to a set of related constant values correctly describes enums as naming related constant values.

3. Final Answer:

   To give meaningful names to a set of related constant values -> Option A

4. Quick Check:

   Enum = Named constants [OK]

Hint: Enums name fixed sets of values clearly [OK]

Common Mistakes:

• Thinking enums create classes
• Confusing enums with variables
• Assuming enums store unrelated data

2. Which of the following is the correct syntax to declare an enum named Day with values Monday, Tuesday, and Wednesday?

easy

A. enum Day (Monday, Tuesday, Wednesday);

B. enum Day { Monday, Tuesday, Wednesday }

C. enum Day: Monday, Tuesday, Wednesday;

D. enum Day = { Monday, Tuesday, Wednesday };

Solution

1. Step 1: Recall enum declaration syntax

   In C#, enums are declared with the keyword enum, name, and curly braces listing values separated by commas.

2. Step 2: Match syntax to options

   enum Day { Monday, Tuesday, Wednesday } matches the correct syntax: enum Day { Monday, Tuesday, Wednesday }.

3. Final Answer:

   enum Day { Monday, Tuesday, Wednesday } -> Option B

4. Quick Check:

   Enum syntax uses braces and commas [OK]

Hint: Use braces and commas to list enum values [OK]

Common Mistakes:

• Using equals sign (=) after enum name
• Using colons or parentheses incorrectly
• Missing commas between values

3. Given the enum and switch code below, what will be printed?

enum Color { Red, Green, Blue }

Color c = Color.Green;
switch (c)
{
    case Color.Red:
        Console.WriteLine("Stop");
        break;
    case Color.Green:
        Console.WriteLine("Go");
        break;
    case Color.Blue:
        Console.WriteLine("Wait");
        break;
}

medium

A. Go

B. Stop

C. Wait

D. No output

Solution

1. Step 1: Identify the enum value assigned

   The variable c is assigned Color.Green.

2. Step 2: Follow switch cases for Color.Green

   The switch matches Color.Green and prints "Go".

3. Final Answer:

   Go -> Option A

4. Quick Check:

   Switch on enum Green prints "Go" [OK]

Hint: Match enum value to switch case output [OK]

Common Mistakes:

• Confusing enum values with strings
• Missing break causing fall-through
• Assuming default case runs without match

4. What is wrong with the following code snippet?

enum Status { Pending, Approved, Rejected }

Status s = Status.Approved;
switch (s)
{
    case Status.Pending:
        Console.WriteLine("Waiting");
    case Status.Approved:
        Console.WriteLine("Accepted");
        break;
    case Status.Rejected:
        Console.WriteLine("Denied");
        break;
}

medium

A. Variable s is not assigned a value

B. Enum values are not declared correctly

C. Switch statement syntax is invalid

D. Missing break after case Status.Pending causes fall-through

Solution

1. Step 1: Check switch cases for breaks

   The case Status.Pending lacks a break;, so execution falls through to the next case.

2. Step 2: Understand fall-through effect

   If s was Status.Pending, it would print both "Waiting" and "Accepted" unintentionally.

3. Final Answer:

   Missing break after case Status.Pending causes fall-through -> Option D

4. Quick Check:

   Each switch case needs a break [OK]

Hint: Always add break after each switch case [OK]

Common Mistakes:

• Forgetting break causes multiple case runs
• Assuming enum declaration is wrong
• Thinking variable is uninitialized

5. You want to write a method that takes an enum Season with values Spring, Summer, Fall, Winter and returns a string describing the typical weather. Which switch expression correctly returns "Warm" for Summer and Spring, "Cool" for Fall, and "Cold" for Winter?

hard

A. return season switch {
Season.Spring, Season.Summer => "Warm",
Season.Fall => "Cold",
Season.Winter => "Cool"
};

B. switch (season) {
case Season.Spring:
case Season.Summer:
return "Warm";
case Season.Fall:
return "Cool";
case Season.Winter:
return "Cold";
default:
return "Unknown";
}

C. return season switch {
Season.Spring => "Warm",
Season.Summer => "Warm",
Season.Fall => "Cool",
Season.Winter => "Cold",
_ => "Unknown"
};

D. switch (season) {
case Season.Spring:
return "Warm";
case Season.Summer:
return "Cool";
case Season.Fall:
return "Cold";
case Season.Winter:
return "Cold";
}

Solution

1. Step 1: Check switch expression syntax

   return season switch { Season.Spring => "Warm", Season.Summer => "Warm", Season.Fall => "Cool", Season.Winter => "Cold", _ => "Unknown" }; uses the modern C# switch expression with correct syntax and covers all enum values with correct returns.

2. Step 2: Verify correct mapping of seasons to weather

   Spring and Summer return "Warm", Fall returns "Cool", Winter returns "Cold", and a default case handles unknowns.

3. Final Answer:

   return season switch { Season.Spring => "Warm", Season.Summer => "Warm", Season.Fall => "Cool", Season.Winter => "Cold", _ => "Unknown" }; -> Option C

4. Quick Check:

   Switch expression with correct mappings [OK]

Hint: Use switch expressions for concise enum mapping [OK]

Common Mistakes:

• Using incorrect syntax for multiple values in switch expression
• Mixing return values incorrectly
• Missing default case in switch expression