Enum declaration syntax in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this enum usage?

Consider this C# code snippet. What will be printed when it runs?

C Sharp (C#)

enum Days { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }

class Program {
    static void Main() {
        Days today = Days.Wednesday;
        Console.WriteLine((int)today);
    }
}

A 0

B 2

C 3

D 4

💡 Hint

Remember enums start numbering from 0 by default.

By default, the first enum member has the value 0, so Sunday=0, Monday=1, Tuesday=2, Wednesday=3. Casting Wednesday to int prints 3.

❓ Predict Output

intermediate

What is the output of this enum with custom values?

Look at this enum with assigned values. What does the program print?

C Sharp (C#)

enum Status { Pending = 1, Active = 5, Closed = 10 }

class Program {
    static void Main() {
        Status s = Status.Active;
        Console.WriteLine((int)s);
    }
}

A 5

B 10

C 1

D 0

💡 Hint

Check the assigned value for Active.

Active is explicitly assigned the value 5, so casting it to int prints 5.

❓ Predict Output

advanced

What error does this enum declaration cause?

What error will this code produce when compiled?

C Sharp (C#)

enum Colors { Red, Green = 5, Blue, Green = 10 }

class Program {
    static void Main() {}
}

A Compile-time error: Enum values must be unique

B Runtime error: Duplicate enum member

C No error, compiles successfully

D Compile-time error: Duplicate enum member name

💡 Hint

Check if enum member names can repeat.

Enum member names must be unique. Declaring 'Green' twice causes a compile-time error.

❓ Predict Output

advanced

What is the output of this enum with flags attribute?

Given this code using [Flags], what will be printed?

C Sharp (C#)

[Flags]
enum Permissions {
    None = 0,
    Read = 1,
    Write = 2,
    Execute = 4
}

class Program {
    static void Main() {
        Permissions p = Permissions.Read | Permissions.Write;
        Console.WriteLine(p);
    }
}

A Read, Write

B 3

C Read Write

D 1, 2

💡 Hint

The [Flags] attribute changes how the enum prints combined values.

With [Flags], combined enum values print as a comma-separated list of names.

🧠 Conceptual

expert

Which enum declaration is valid and assigns correct values?

Which of these enum declarations compiles without error and assigns the values as shown?

A enum Levels { Low = 1, Medium = 2, High = 5, Critical = 5 } // Duplicate value 5

B enum Levels { Low = 1, Medium, High = 5, Critical } // Low=1, Medium=2, High=5, Critical=6

C enum Levels { Low, Medium = 2, High, Critical } // Low=0, Medium=2, High=3, Critical=4

D enum Levels { Low = 1, Medium = 2, High, Critical = 2 } // Duplicate value 2

💡 Hint

Check how enum values increment when not explicitly assigned.

Option B is valid: Medium gets 2 automatically after Low=1; Critical gets 6 after High=5. Duplicate values are allowed but not in options B and D as stated.

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