Switch vs if comparison - Hands-On Comparison

Switch vs if comparison

📖 Scenario: Imagine you are creating a simple program that tells the day of the week based on a number. You want to see how using switch and if statements can both solve this problem.

🎯 Goal: Build a program that takes a number from 1 to 7 and prints the corresponding day of the week using both switch and if statements.

📋 What You'll Learn

Create an integer variable called day with a value of 3

Use a switch statement with day to print the correct day name

Use an if statement with day to print the correct day name

Print the results for both switch and if methods

💡 Why This Matters

🌍 Real World

Choosing actions based on a value is common in programs, like menus or commands.

💼 Career

Understanding switch and if statements is essential for writing clear and efficient code in many programming jobs.

1

Create the day variable

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

C

// Create an integer variable called day and set it to 3
// Your code here

Hint

Use int day = 3; to create the variable.

2

Add a switch statement for day

Add a switch statement using the variable day to print the day name for 1 to 7. For 3, print "Wednesday". Use printf inside each case.

C

#include 

int main() {
    int day = 3;
    // Add switch statement here
    // Your code here
    return 0;
}

Hint

Use switch(day) { case 1: ... } and printf for each day.

3

Add an if statement for day

Add an if statement using the variable day to print the day name for 1 to 7. For 3, print "Wednesday". Use printf inside each condition.

C

#include 

int main() {
    int day = 3;
    switch(day) {
        case 1:
            printf("Monday\n");
            break;
        case 2:
            printf("Tuesday\n");
            break;
        case 3:
            printf("Wednesday\n");
            break;
        case 4:
            printf("Thursday\n");
            break;
        case 5:
            printf("Friday\n");
            break;
        case 6:
            printf("Saturday\n");
            break;
        case 7:
            printf("Sunday\n");
            break;
        default:
            printf("Invalid day\n");
    }
    // Add if statement here
    // Your code here
    return 0;
}

Hint

Use if(day == 1) { ... } else if(day == 2) { ... } and so on.

4

Print the final output

Run the program and observe the output. It should print Wednesday twice, once from the switch and once from the if statement. Write a printf statement before each to label them as Switch: and If:.

C

#include 

int main() {
    int day = 3;
    // Print label for switch
    // Your code here
    switch(day) {
        case 1:
            printf("Monday\n");
            break;
        case 2:
            printf("Tuesday\n");
            break;
        case 3:
            printf("Wednesday\n");
            break;
        case 4:
            printf("Thursday\n");
            break;
        case 5:
            printf("Friday\n");
            break;
        case 6:
            printf("Saturday\n");
            break;
        case 7:
            printf("Sunday\n");
            break;
        default:
            printf("Invalid day\n");
    }

    // Print label for if
    // Your code here
    if(day == 1) {
        printf("Monday\n");
    } else if(day == 2) {
        printf("Tuesday\n");
    } else if(day == 3) {
        printf("Wednesday\n");
    } else if(day == 4) {
        printf("Thursday\n");
    } else if(day == 5) {
        printf("Friday\n");
    } else if(day == 6) {
        printf("Saturday\n");
    } else if(day == 7) {
        printf("Sunday\n");
    } else {
        printf("Invalid day\n");
    }

    return 0;
}

Hint

Use printf("Switch: "); before the switch and printf("If: "); before the if.

Practice

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

easy

A. switch is best for checking one variable against many fixed values.

B. switch can handle complex range conditions better than if.

C. if is only used for simple true/false checks.

D. if cannot be used with multiple conditions.

Solution

1. Step 1: Understand switch usage

   switch works well when you compare one variable to many fixed values like 1, 2, 3.

2. Step 2: Compare with if

   if is more flexible and can handle ranges or complex conditions, but switch is clearer for fixed values.

3. Final Answer:

   switch is best for checking one variable against many fixed values. -> Option A

4. Quick Check:

   Use switch for fixed values [OK]

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

Common Mistakes:

• Thinking switch handles ranges
• Believing if can't handle multiple conditions
• Confusing switch with if for complex logic

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: Check switch syntax

   The correct syntax uses parentheses around the variable and curly braces for cases.

2. Step 2: Identify correct case and break usage

   Each case ends with a colon and usually a break to prevent fall-through.

3. Final Answer:

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

4. Quick Check:

   Parentheses + cases + breaks = correct switch [OK]

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

Common Mistakes:

• Omitting parentheses around variable
• Using if inside switch incorrectly
• Missing break causing fall-through

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

int x = 2;
switch (x) {
  case 1: printf("One\n"); break;
  case 2: printf("Two\n");
  case 3: printf("Three\n"); break;
  default: printf("Default\n");
}

medium

A. Two

B. Two
Three

C. Three

D. Default

Solution

1. Step 1: Identify matching case

   The variable x is 2, so case 2 matches and prints "Two".

2. Step 2: Check for break after case 2

   There is no break after case 2, so execution falls through to case 3 and prints "Three".

3. Final Answer:

   Two Three -> Option B

4. Quick Check:

   Missing break causes fall-through [OK]

Hint: No break after case causes next case to run too [OK]

Common Mistakes:

• Assuming break after every case automatically
• Ignoring fall-through behavior
• Thinking default runs if case matches

4. Find the error in this code snippet:

int num = 3;
switch (num) {
  case 1:
    printf("One\n");
  case 2:
    printf("Two\n");
    break;
  default:
    printf("Default\n");
}

medium

A. Case labels must be strings, not numbers.

B. Switch variable must be a character, not int.

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

D. Default case must be last, but it is not.

Solution

1. Step 1: Check breaks after cases

   Case 1 lacks a break, so if num is 1, it will fall through to case 2 and print both lines.

2. Step 2: Validate switch rules

   Switch can use int variables, default can be anywhere, and case labels are numbers here, which is correct.

3. Final Answer:

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

4. Quick Check:

   Always add break to avoid fall-through [OK]

Hint: Add break after each case to prevent fall-through [OK]

Common Mistakes:

• Thinking switch only works with chars
• Believing default must be last
• Confusing case label types

5. You want to print a message based on a score variable:
- "Fail" if score < 50
- "Pass" if score is between 50 and 75 inclusive
- "Excellent" if score > 75

Which approach is best in C?

hard

A. Use a switch with default only and if inside cases.

B. Use a switch statement with cases for each score range.

C. Use multiple switch statements for each condition.

D. Use if-else statements to check score ranges.

Solution

1. Step 1: Analyze score conditions

   The conditions involve ranges (less than 50, between 50 and 75, greater than 75).

2. Step 2: Choose suitable control structure

   Switch works only with fixed values, not ranges, so if-else is better for ranges.

3. Final Answer:

   Use if-else statements to check score ranges. -> Option D

4. Quick Check:

   Ranges need if-else, not switch [OK]

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

Common Mistakes:

• Trying to use switch for ranges
• Using multiple switches unnecessarily
• Confusing default case with range checks