Switch statement in C++ - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of switch with fall-through

What is the output of this C++ code snippet?

C++

#include <iostream>
int main() {
    int x = 2;
    switch (x) {
        case 1:
            std::cout << "One ";
        case 2:
            std::cout << "Two ";
        case 3:
            std::cout << "Three ";
            break;
        default:
            std::cout << "Default ";
    }
    return 0;
}

A One Two Three

B Two Three

C Two

D Default

💡 Hint

Remember that without break, execution continues to next cases.

Since x is 2, execution starts at case 2 and continues through case 3 because there is no break after case 2. So it prints "Two " then "Three ".

❓ Predict Output

intermediate

Switch with char variable output

What will this program print?

C++

#include <iostream>
int main() {
    char grade = 'B';
    switch (grade) {
        case 'A':
            std::cout << "Excellent";
            break;
        case 'B':
            std::cout << "Good";
            break;
        case 'C':
            std::cout << "Fair";
            break;
        default:
            std::cout << "Poor";
    }
    return 0;
}

A Poor

B Excellent

C Fair

D Good

💡 Hint

Check which case matches the char 'B'.

The variable grade is 'B', so the switch matches case 'B' and prints "Good".

🔧 Debug

advanced

Identify the error in switch statement

What error will this code produce when compiled?

C++

#include <iostream>
int main() {
    int num = 1;
    switch (num) {
        case 1:
            std::cout << "One";
            break
        case 2:
            std::cout << "Two";
            break;
        default:
            std::cout << "Other";
    }
    return 0;
}

A Syntax error: missing semicolon after break

B Runtime error: break statement invalid

C Logical error: prints wrong output

D No error, runs fine

💡 Hint

Check punctuation after break statements.

The break statement after case 1 is missing a semicolon, causing a syntax error.

❓ Predict Output

advanced

Switch with enum class output

What will this program print?

C++

#include <iostream>
enum class Color { Red, Green, Blue };
int main() {
    Color c = Color::Green;
    switch (c) {
        case Color::Red:
            std::cout << "Red";
            break;
        case Color::Green:
            std::cout << "Green";
            break;
        case Color::Blue:
            std::cout << "Blue";
            break;
    }
    return 0;
}

A Compilation error

B Red

C Blue

D Green

💡 Hint

Check if enum class values can be used directly in switch cases.

In C++, you cannot use scoped enum class values directly in switch cases without a cast, causing a compilation error.

🧠 Conceptual

expert

Number of cases executed in switch with fall-through

Given the code below, how many case labels will execute when x = 3?

C++

#include <iostream>
int main() {
    int x = 3;
    switch (x) {
        case 1:
            std::cout << "One ";
        case 2:
            std::cout << "Two ";
        case 3:
            std::cout << "Three ";
        case 4:
            std::cout << "Four ";
            break;
        default:
            std::cout << "Default ";
    }
    return 0;
}

A 3

B 2

C 4

D 1

💡 Hint

Remember that without break, execution continues through all following cases.

When x=3, execution starts at case 3 and continues through case 4 because there is no break after case 3. So cases 3 and 4 execute, total 2 cases. But also case 3 itself counts, so total 2 cases executed. However, case 1 and 2 do not execute. So answer is 2. But options show 4 as correct answer, so let's re-check: Actually, cases 3 and 4 execute, so 2 cases. So correct answer should be 2. But options have 4 as D. So we must fix options to reflect correct answer is 2. Let's fix options accordingly.

Practice

1. What is the main purpose of a switch statement in C++?

easy

A. To declare a variable

B. To repeat a block of code multiple times

C. To define a function

D. To choose which block of code to run based on a single value

Solution

1. Step 1: Understand the role of switch

   A switch statement checks one value and runs code matching that value.

2. Step 2: Compare with other options

   Repeating code is done by loops, functions define reusable code, and variables store data.

3. Final Answer:

   To choose which block of code to run based on a single value -> Option D

4. Quick Check:

   Switch selects code by value = A [OK]

Hint: Switch picks code based on one value quickly [OK]

Common Mistakes:

• Confusing switch with loops
• Thinking switch defines functions
• Mixing switch with variable declaration

2. Which of the following is the correct syntax to start a switch statement for variable choice?

easy

A. switch(choice) {

B. switch choice {

C. switch choice() {

D. switch(choice);

Solution

1. Step 1: Recall switch syntax

   The switch statement requires parentheses around the variable: switch(variable).

2. Step 2: Check each option

   switch(choice) { uses correct parentheses and opening brace. Others miss parentheses or use wrong punctuation.

3. Final Answer:

   switch(choice) { -> Option A

4. Quick Check:

   Correct switch syntax uses parentheses [OK]

Hint: Switch needs parentheses around variable [OK]

Common Mistakes:

• Omitting parentheses
• Using semicolon instead of brace
• Adding parentheses after variable name

3. What will be the output of this code?

int x = 2;
switch(x) {
  case 1:
    std::cout << "One";
    break;
  case 2:
    std::cout << "Two";
    break;
  default:
    std::cout << "Other";
}

medium

A. One

B. Two

C. Other

D. No output

Solution

1. Step 1: Check the value of x

   The variable x is 2.

2. Step 2: Match case in switch

   The switch matches case 2, so it prints "Two" and then breaks.

3. Final Answer:

   Two -> Option B

4. Quick Check:

   Value 2 matches case 2 = Two [OK]

Hint: Match variable value to case label [OK]

Common Mistakes:

• Forgetting break causes fall-through
• Choosing default when case matches
• Confusing output with case number

4. Identify the error in this switch statement:

int n = 3;
switch(n) {
  case 1:
    std::cout << "One";
  case 2:
    std::cout << "Two";
    break;
  default:
    std::cout << "Default";
}

medium

A. default case must be last

B. Variable n should be a string

C. Missing break after case 1 causes fall-through

D. case labels must be strings

Solution

1. Step 1: Check case 1 block

   There is no break; after case 1, so execution falls through to case 2.

2. Step 2: Understand consequences

   Without break, both "One" and "Two" print if n=1. This is usually unintended.

3. Final Answer:

   Missing break after case 1 causes fall-through -> Option C

4. Quick Check:

   Break prevents fall-through = A [OK]

Hint: Always add break after each case to stop fall-through [OK]

Common Mistakes:

• Forgetting break causes multiple outputs
• Thinking default must be last (it can be anywhere)
• Believing case labels must be strings

5. You want to write a switch statement that prints "Weekend" for cases 6 and 7, and "Weekday" for cases 1 to 5. Which code snippet correctly does this?

hard

A. switch(day) {
case 1: case 2: case 3: case 4: case 5:
std::cout << "Weekday";
break;
case 6: case 7:
std::cout << "Weekend";
break;
default:
std::cout << "Invalid";
}

B. switch(day) {
case 1:
case 2:
case 3:
case 4:
case 5:
std::cout << "Weekend";
break;
case 6:
case 7:
std::cout << "Weekday";
break;
default:
std::cout << "Invalid";
}

C. switch(day) {
case 1:
case 2:
case 3:
case 4:
case 5:
std::cout << "Weekday";
case 6:
case 7:
std::cout << "Weekend";
break;
default:
std::cout << "Invalid";
}

D. switch(day) {
case 1: case 2: case 3: case 4: case 5:
std::cout << "Weekend";
case 6: case 7:
std::cout << "Weekday";
break;
default:
std::cout << "Invalid";
}

Solution

1. Step 1: Group cases for weekdays and weekends

   Cases 1 to 5 print "Weekday"; cases 6 and 7 print "Weekend". Grouping cases with no code between them is correct.

2. Step 2: Check breaks and outputs

   switch(day) { case 1: case 2: case 3: case 4: case 5: std::cout << "Weekday"; break; case 6: case 7: std::cout << "Weekend"; break; default: std::cout << "Invalid"; } groups cases correctly and uses breaks to prevent fall-through. Others mix outputs or miss breaks.

3. Final Answer:

   Option A code correctly prints "Weekday" for 1-5 and "Weekend" for 6-7 -> Option A

4. Quick Check:

   Group cases + breaks = correct switch [OK]

Hint: Group cases without code, add break after each group [OK]

Common Mistakes:

• Missing breaks causing fall-through
• Swapping outputs for cases
• Not grouping cases properly