Switch vs if comparison in C++ - Practice Questions

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 Two Three

B One Two Three

C Three

D Default

💡 Hint

Remember that switch cases fall through unless you use break.

The switch starts at case 2, prints "Two ", then falls through to case 3 and prints "Three ". It stops at break.

❓ Predict Output

intermediate

If-else chain output

What is the output of this C++ code using if-else?

C++

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

A Two

B One Two

C Two Three

D Default

💡 Hint

If-else stops checking after the first true condition.

The condition x == 2 is true, so it prints "Two " and skips the rest.

🧠 Conceptual

advanced

Switch statement limitations

Which of the following is NOT a limitation of the C++ switch statement compared to if-else?

A Switch only works with integral or enum types, not with strings or floats.

B Switch cannot evaluate complex conditions like ranges or multiple variables.

C Switch cases must be constant expressions known at compile time.

D Switch statements always execute all cases regardless of matching.

💡 Hint

Think about how switch chooses which case to run.

Switch executes only the matching case and any following cases if no break is used. It does NOT always execute all cases.

❓ Predict Output

advanced

Output difference between switch and if

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

C++

#include <iostream>
int main() {
    int x = 5;
    switch (x) {
        case 1:
            std::cout << "One ";
            break;
        case 2:
            std::cout << "Two ";
            break;
        default:
            std::cout << "Default switch ";
    }
    if (x == 1) {
        std::cout << "One if ";
    } else if (x == 2) {
        std::cout << "Two if ";
    } else {
        std::cout << "Default if ";
    }
    return 0;
}

A Default if

B Default switch

C Default switch Default if

D One if

💡 Hint

Both switch and if-else handle default cases here.

The switch hits default and prints "Default switch ". The if-else hits else and prints "Default if ". Both outputs appear.

🧠 Conceptual

expert

When to prefer switch over if-else

Which scenario best justifies using a switch statement instead of if-else in C++?

A When you need to check multiple unrelated conditions involving different variables and complex expressions.

B When you have a single variable with many possible constant integral values to handle distinctly.

C When you want to evaluate ranges or conditions involving inequalities.

D When you want to execute code based on string comparisons.

💡 Hint

Switch works best with one variable and fixed values.

Switch is ideal for one variable with many constant integral values. It is not suitable for complex conditions, ranges, or strings.

Practice

1. Which statement best describes when to use switch instead of if in C++?

easy

A. switch can handle complex conditions like ranges.

B. if cannot be used with multiple conditions.

C. if is only for checking equality.

D. switch is best for many fixed, discrete values.

Solution

1. Step 1: Understand switch usage

   switch works well when you have many fixed values to compare, like numbers or characters.

2. Step 2: Compare with if

   if can handle any condition, including ranges or complex logic, but switch is simpler for fixed choices.

3. Final Answer:

   switch is best for many fixed, discrete values. -> Option D

4. Quick Check:

   Use switch for fixed values = B [OK]

Hint: Use switch for fixed values, if for complex conditions [OK]

Common Mistakes:

• Thinking switch can handle ranges
• Believing if is only for equality
• Assuming if cannot handle multiple conditions

2. Which of the following is the correct syntax for a switch statement in C++?

easy

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

B. switch (variable) { case 1: doSomething(); break; default: doDefault(); }

C. switch (variable) do { case 1: doSomething(); break; }

D. switch (variable) { if case 1: doSomething(); }

Solution

1. Step 1: Recall correct switch syntax

   The switch statement requires parentheses around the variable and curly braces enclosing cases.

2. Step 2: Check each option

   switch (variable) { case 1: doSomething(); break; default: doDefault(); } uses correct syntax with parentheses, cases, and breaks. Others miss parentheses, use wrong keywords, or incorrect structure.

3. Final Answer:

   switch (variable) { case 1: doSomething(); break; default: doDefault(); } -> Option B

4. Quick Check:

   Parentheses and braces needed in switch = A [OK]

Hint: Remember switch(variable) with braces and cases [OK]

Common Mistakes:

• Omitting parentheses around variable
• Using 'if' inside switch incorrectly
• Missing curly braces for cases

3. What will be the output of this C++ code?

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

medium

A. TwoThree

B. Two

C. Three

D. Other

Solution

1. Step 1: Identify matching case

   The variable x is 2, so the switch jumps to case 2.

2. Step 2: Trace output and breaks

   It prints "Two" but no break after case 2, so it continues to case 3 and prints "Three" before breaking.

3. Final Answer:

   TwoThree -> Option A

4. Quick Check:

   Missing break causes fall-through = TwoThree [OK]

Hint: Remember missing break causes fall-through in switch [OK]

Common Mistakes:

• Assuming only case 2 prints
• Forgetting fall-through behavior
• Confusing default case execution

4. Identify the error in this code snippet:

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. Switch variable must be a string.

C. Missing break after case 1 causes fall-through.

D. Case labels must be in ascending order.

Solution

1. Step 1: Check switch cases and breaks

   Case 1 lacks a break, so if n == 1, it will fall through to case 2 and print both outputs.

2. Step 2: Verify other rules

   Switch variable can be int, default can be anywhere, and case order does not matter.

3. Final Answer:

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

4. Quick Check:

   Break needed to prevent fall-through = A [OK]

Hint: Always add break after each case unless fall-through wanted [OK]

Common Mistakes:

• Thinking switch variable must be string
• Believing default must be last
• Assuming case order matters

5. You want to check if an integer variable score is between 90 and 100 (inclusive) to print "Excellent", between 75 and 89 to print "Good", and otherwise print "Try again". Which approach is better and why?

hard

A. Use if because switch cannot handle ranges.

B. Use if only for equality checks.

C. Use switch with multiple cases for each number in the range.

D. Use switch because it is simpler for ranges.

Solution

1. Step 1: Understand the problem with ranges

   The conditions check if score falls within ranges, not fixed values.

2. Step 2: Compare switch and if suitability

   switch cannot directly handle ranges; if can use relational operators to check ranges easily.

3. Final Answer:

   Use if because switch cannot handle ranges. -> Option A

4. Quick Check:

   Ranges need if, not switch = D [OK]

Hint: Use if for ranges, switch only for fixed values [OK]

Common Mistakes:

• Trying to use switch for ranges
• Using switch with many case labels for ranges
• Thinking if only checks equality