Switch vs if comparison in C++ - Hands-On Comparison

Switch vs if comparison

📖 Scenario: Imagine you are building a simple program that tells the day of the week based on a number input. You want to compare two ways to do this: using switch and using if statements.

🎯 Goal: You will create a program that takes a number from 1 to 7 and prints the corresponding day name. You will first set up the input number, then create a variable to hold the day name, then use switch statement to assign the correct day name to dayName, and finally print the result.

📋 What You'll Learn

Create an integer variable called dayNumber with the value 3

Create a string variable called dayName initialized to an empty string

Use a switch statement on dayNumber to assign the correct day name to dayName

Print the value of dayName

💡 Why This Matters

🌍 Real World

Programs often need to choose actions based on a value, like days of the week or menu options.

💼 Career

Understanding switch and if statements is essential for writing clear, efficient decision-making code in many software jobs.

1

Set up the day number

Create an integer variable called dayNumber and set it to 3.

C++

# Your code here

Hint

Use int dayNumber = 3; to create the variable.

2

Create the day name variable

Create a string variable called dayName and initialize it to an empty string "".

C++

int dayNumber = 3;
// Your code here

Hint

Use std::string dayName = ""; to create the variable.

3

Assign day name using switch

Use a switch statement on dayNumber to assign the correct day name to dayName. Use these mappings: 1 = "Monday", 2 = "Tuesday", 3 = "Wednesday", 4 = "Thursday", 5 = "Friday", 6 = "Saturday", 7 = "Sunday". Include a default case that assigns "Invalid day".

C++

int dayNumber = 3;
std::string dayName = "";
// Your code here

Hint

Use switch(dayNumber) { case 1: dayName = "Monday"; break; ... default: dayName = "Invalid day"; }

4

Print the day name

Write a std::cout statement to print the value of dayName followed by a newline.

C++

int dayNumber = 3;
std::string dayName = "";
switch(dayNumber) {
    case 1:
        dayName = "Monday";
        break;
    case 2:
        dayName = "Tuesday";
        break;
    case 3:
        dayName = "Wednesday";
        break;
    case 4:
        dayName = "Thursday";
        break;
    case 5:
        dayName = "Friday";
        break;
    case 6:
        dayName = "Saturday";
        break;
    case 7:
        dayName = "Sunday";
        break;
    default:
        dayName = "Invalid day";
}
// Your code here

Hint

Use std::cout << dayName << std::endl; to print the day name.

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