Enum with switch pattern in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Enum switch expression

What is the output of the following C# code?

C Sharp (C#)

enum TrafficLight { Red, Yellow, Green }

class Program {
    static string GetAction(TrafficLight light) => light switch {
        TrafficLight.Red => "Stop",
        TrafficLight.Yellow => "Caution",
        TrafficLight.Green => "Go",
        _ => "Unknown"
    };

    static void Main() {
        System.Console.WriteLine(GetAction(TrafficLight.Yellow));
    }
}

A Caution

B Go

C Stop

D Unknown

💡 Hint

Look at the switch expression matching the enum value Yellow.

The switch expression matches TrafficLight.Yellow and returns "Caution".

❓ Predict Output

intermediate

Switch expression with default case output

What will this C# program print when run?

C Sharp (C#)

enum Season { Spring, Summer, Autumn, Winter }

class Program {
    static string Describe(Season s) => s switch {
        Season.Spring => "Flowers bloom",
        Season.Summer => "Sun shines",
        _ => "Cold season"
    };

    static void Main() {
        System.Console.WriteLine(Describe(Season.Winter));
    }
}

A Sun shines

B Cold season

C Compilation error

D Flowers bloom

💡 Hint

Check which case matches Season.Winter in the switch expression.

Winter is not explicitly matched, so the default case '_' returns "Cold season".

🔧 Debug

advanced

Identify the error in enum switch pattern

What error will this C# code produce when compiled?

C Sharp (C#)

enum Direction { North, East, South, West }

class Program {
    static string Turn(Direction d) => d switch {
        Direction.North => "Go up",
        Direction.East => "Go right",
        Direction.South => "Go down"
    };

    static void Main() {
        System.Console.WriteLine(Turn(Direction.West));
    }
}

A CS8509: The switch expression does not handle all possible values

B System.InvalidOperationException at runtime

C CS0128: A local variable is already defined

D No error, prints "Go right"

💡 Hint

Check if the switch expression covers all enum values.

The switch expression misses Direction.West and has no default case, causing CS8509 compile error.

❓ Predict Output

advanced

Output of nested switch with enum

What is the output of this C# program?

C Sharp (C#)

enum Mode { Auto, Manual }
enum Status { On, Off }

class Program {
    static string GetMessage(Mode m, Status s) => m switch {
        Mode.Auto => s switch {
            Status.On => "Auto mode ON",
            Status.Off => "Auto mode OFF"
        },
        Mode.Manual => s switch {
            Status.On => "Manual mode ON",
            Status.Off => "Manual mode OFF"
        },
        _ => "Unknown mode"
    };

    static void Main() {
        System.Console.WriteLine(GetMessage(Mode.Manual, Status.Off));
    }
}

A Auto mode ON

B Manual mode ON

C Manual mode OFF

D Unknown mode

💡 Hint

Look at the nested switch for Mode.Manual and Status.Off.

For Mode.Manual and Status.Off, the nested switch returns "Manual mode OFF".

🧠 Conceptual

expert

Exhaustiveness in enum switch expressions

Which statement about C# switch expressions with enums is TRUE?

A You can only use switch statements, not switch expressions, with enums in C#.

B Switch expressions on enums always compile even if some enum values are missing cases.

C Switch expressions on enums do not support pattern matching.

D A switch expression on an enum must include a default case or cover all enum values to compile.

💡 Hint

Think about compiler checks for switch expressions on enums.

C# requires switch expressions on enums to be exhaustive by covering all enum values or having a default case.

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