Switch vs if comparison - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "One" when variable x equals 1 using if statement.

C

if (x [1] 1) {
    printf("One\n");
}

Drag options to blanks, or click blank then click option'

A!=

B=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '==' causes assignment, not comparison.

The operator == checks if x is equal to 1 in an if statement.

2fill in blank

medium

Complete the switch statement to handle the case when variable c equals 'a'.

C

switch(c) {
    case [1]:
        printf("Letter a\n");
        break;
}

Drag options to blanks, or click blank then click option'

A'b'

B'a'

C'c'

D'd'

Attempts:

3 left

💡 Hint

Common Mistakes

Using double quotes instead of single quotes for characters.

The case label must match the value to check, so 'a' is correct.

3fill in blank

hard

Fix the error in the if statement condition to correctly check if n is not equal to 0.

C

if (n [1] 0) {
    printf("Non-zero\n");
}

Drag options to blanks, or click blank then click option'

A!=

B<=

C=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '!=' causes assignment, not comparison.

The operator != checks if n is not equal to 0.

4fill in blank

hard

Fill both blanks to complete the switch statement that prints "Weekend" for 6 or 7.

C

switch(day) {
    case [1]:
    case [2]:
        printf("Weekend\n");
        break;
}

Drag options to blanks, or click blank then click option'

A6

B5

C7

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong case numbers for weekend days.

Cases 6 and 7 represent weekend days in this example.

5fill in blank

hard

Fill all three blanks to complete the if-else chain that prints the day type based on day number.

C

if (day [1] 6 || day [2] 7) {
    printf("Weekend\n");
} else if (day [3] 1 && day <= 5) {
    printf("Weekday\n");
}

Drag options to blanks, or click blank then click option'

A==

B>=

C<=

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong logical operators or comparison signs.

The first two blanks check if day equals 6 or 7. The last blank uses '>=' to check if day is between 1 and 5.

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