Switch statement execution in C Sharp (C#)

Introduction

A switch statement helps you choose what to do based on different values. It makes your code cleaner and easier to read when you have many options.

You want to perform different actions depending on a variable's value.

You have many conditions to check against one variable.

You want to avoid writing many if-else statements.

You want your code to be easier to understand and maintain.

Syntax

C Sharp (C#)

switch (variable)
{
    case value1:
        // code to run if variable == value1
        break;
    case value2:
        // code to run if variable == value2
        break;
    default:
        // code to run if variable does not match any case
        break;
}

Each case checks if the variable matches a value.

The break stops the switch from running other cases.

Examples

This example prints the name of the day based on the number.

C Sharp (C#)

int day = 3;
switch (day)
{
    case 1:
        Console.WriteLine("Monday");
        break;
    case 2:
        Console.WriteLine("Tuesday");
        break;
    case 3:
        Console.WriteLine("Wednesday");
        break;
    default:
        Console.WriteLine("Unknown day");
        break;
}

This example shows how multiple cases can share the same code.

C Sharp (C#)

char grade = 'B';
switch (grade)
{
    case 'A':
        Console.WriteLine("Excellent");
        break;
    case 'B':
    case 'C':
        Console.WriteLine("Well done");
        break;
    case 'D':
        Console.WriteLine("You passed");
        break;
    default:
        Console.WriteLine("Try again");
        break;
}

Sample Program

This program checks the value of number and prints a message for 1, 2, or 3. If the number is not 1, 2, or 3, it prints "Number is unknown".

C Sharp (C#)

using System;

class Program
{
    static void Main()
    {
        int number = 2;
        switch (number)
        {
            case 1:
                Console.WriteLine("Number is one");
                break;
            case 2:
                Console.WriteLine("Number is two");
                break;
            case 3:
                Console.WriteLine("Number is three");
                break;
            default:
                Console.WriteLine("Number is unknown");
                break;
        }
    }
}

Important Notes

Always include a default case to handle unexpected values.

Forgetting break can cause the program to run multiple cases unintentionally.

Summary

Switch statements help choose actions based on a variable's value.

Use case for each value and break to stop.

Include a default case for any other values.

Practice

1.

What is the main purpose of a switch statement in C#?

easy

A. To repeat a block of code multiple times

B. To execute different code blocks based on the value of a variable

C. To define a function

D. To declare variables

Solution

1. Step 1: Understand the role of switch

   A switch statement selects one of many code blocks to execute based on a variable's value.

2. Step 2: Compare with other options

   Loops repeat code, functions define reusable code, and variable declarations create variables, none of which match switch's purpose.

3. Final Answer:

   To execute different code blocks based on the value of a variable -> Option B

4. Quick Check:

   Switch chooses code by value = A [OK]

Hint: Switch chooses code based on variable value [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines functions
• Believing switch declares variables

2.

Which of the following is the correct syntax to start a switch statement in C#?

?

easy

A. switch (variable) { case 1: break; }

B. switch variable { case 1: break; }

C. switch (variable) case 1: break;

D. switch { variable case 1: break; }

Solution

1. Step 1: Recall switch syntax

   The correct syntax uses parentheses around the variable and braces around cases: switch (variable) { ... }

2. Step 2: Check each option

   switch (variable) { case 1: break; } matches correct syntax; others miss parentheses or braces or have wrong order.

3. Final Answer:

   switch (variable) { case 1: break; } -> Option A

4. Quick Check:

   Parentheses and braces required = C [OK]

Hint: Switch needs (variable) and { cases } syntax [OK]

Common Mistakes:

• Omitting parentheses around variable
• Missing braces around cases
• Incorrect order of keywords

3.

What will be the output of this C# code?

int day = 3;
switch (day) {
  case 1:
    Console.WriteLine("Monday");
    break;
  case 2:
    Console.WriteLine("Tuesday");
    break;
  case 3:
    Console.WriteLine("Wednesday");
    break;
  default:
    Console.WriteLine("Invalid day");
    break;
}

medium

A. Wednesday

B. Monday

C. Tuesday

D. Invalid day

Solution

1. Step 1: Identify the switch variable value

   The variable day is 3.

2. Step 2: Match case with variable

   Case 3 matches, so it prints "Wednesday" and then breaks.

3. Final Answer:

   Wednesday -> Option A

4. Quick Check:

   day=3 prints Wednesday [OK]

Hint: Match variable value to case label [OK]

Common Mistakes:

• Forgetting break causes fall-through
• Choosing default when case matches
• Mixing case numbers and output

4.

Find the error in this switch statement and select the fix:

int number = 2;
switch (number) {
  case 1:
    Console.WriteLine("One");
  case 2:
    Console.WriteLine("Two");
  default:
    Console.WriteLine("Default");
}

medium

A. Add semicolon after switch statement

B. Remove the default case

C. Change switch to if

D. Add break; after each case block

Solution

1. Step 1: Identify missing break statements

   Each case lacks a break, causing fall-through to next cases.

2. Step 2: Fix by adding breaks

   Adding break after each case stops fall-through and executes only matched case.

3. Final Answer:

   Add break; after each case block -> Option D

4. Quick Check:

   Break stops fall-through = A [OK]

Hint: Add break to stop fall-through in switch [OK]

Common Mistakes:

• Ignoring fall-through behavior
• Removing default case unnecessarily
• Misusing if instead of switch

5.

Given this code, what will be printed?

int score = 85;
switch (score / 10) {
  case 10:
  case 9:
    Console.WriteLine("Excellent");
    break;
  case 8:
    Console.WriteLine("Good");
    break;
  case 7:
  case 6:
    Console.WriteLine("Pass");
    break;
  default:
    Console.WriteLine("Fail");
    break;
}

hard

A. Excellent

B. Fail

C. Good

D. Pass

Solution

1. Step 1: Calculate switch expression value

   score is 85, so score / 10 is 8 (integer division).

2. Step 2: Match case for value 8

   Case 8 prints "Good" and breaks.

3. Final Answer:

   Good -> Option C

4. Quick Check:

   85/10=8 prints Good [OK]

Hint: Divide score by 10, match case labels [OK]

Common Mistakes:

• Not using integer division
• Missing combined cases for 9 and 10
• Choosing default incorrectly