If-else expression assignment in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assign the maximum of two numbers to max.

Kotlin

val max = if (a > b) [1] else b

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

Aa + b

Ba

C0

Db

Attempts:

3 left

💡 Hint

Common Mistakes

Using b in the if part instead of a.

Trying to use statements instead of expressions.

The if-else expression returns a if a is greater than b, otherwise b.

2fill in blank

medium

Complete the code to assign a message based on the score.

Kotlin

val message = if (score >= 50) [1] else "Try again"

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

A"Incomplete"

B"Failed"

C"Excellent"

D"Passed"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the else message in the if part.

Forgetting to put quotes around the string.

If the score is 50 or more, the message should be "Passed", otherwise "Try again".

3fill in blank

hard

Fix the error in the if-else expression to assign the correct value.

Kotlin

val result = if (num % 2 == 0) [1] else "Odd"

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

A"Even"

BEven

Cnum

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using Even without quotes causing a compile error.

Returning a boolean or number instead of a string.

The if-else expression must return a string in both cases. "Even" is the correct string for even numbers.

4fill in blank

hard

Fill both blanks to assign a grade based on the score.

Kotlin

val grade = if (score >= [1]) "A" else if (score >= [2]) "B" else "C"

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

A90

B80

C70

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the thresholds for A and B.

Using thresholds that overlap or are out of order.

The highest grade A is for scores 90 and above, grade B for 80 and above, else C.

5fill in blank

hard

Fill all three blanks to assign a description based on temperature.

Kotlin

val description = if (temp < [1]) "Cold" else if (temp < [2]) "Warm" else [3]

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

A10

B25

C"Hot"

D"Cool"

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers instead of strings for descriptions.

Mixing up the order of temperature thresholds.

Temperatures below 10 are "Cold", below 25 are "Warm", and 25 or above are "Hot".

Practice

1. What does the following Kotlin code do?
val result = if (score > 50) "Pass" else "Fail"

easy

A. Assigns "Pass" to result if score is greater than 50, otherwise "Fail"

B. Assigns true if score is greater than 50, otherwise false

C. Throws an error because else is missing

D. Assigns the value of score to result

Solution

1. Step 1: Understand the if-else expression

   The code uses if-else as an expression to assign a value to result based on the condition score > 50.

2. Step 2: Evaluate the condition and assignment

   If score is greater than 50, result gets "Pass"; otherwise, it gets "Fail".

3. Final Answer:

   Assigns "Pass" to result if score is greater than 50, otherwise "Fail" -> Option A

4. Quick Check:

   If-else expression assigns value based on condition [OK]

Hint: If-else expression returns a value, not just controls flow [OK]

Common Mistakes:

• Forgetting the else part causes a syntax error
• Thinking if-else is only for flow, not value assignment
• Confusing condition with assignment

2. Which of the following is the correct syntax for assigning a value using if-else expression in Kotlin?

easy

A. val x = if (a > b) 10 else 20

B. val x if (a > b) = 10 else = 20

C. val x = if a > b then 10 else 20

D. val x = if (a > b) { 10 } else { 20 } else

Solution

1. Step 1: Review Kotlin if-else expression syntax

   The correct syntax uses if(condition) value1 else value2 without extra keywords or misplaced braces.

2. Step 2: Compare options with correct syntax

   val x = if (a > b) 10 else 20 matches the correct syntax: val x = if (a > b) 10 else 20.

3. Final Answer:

   val x = if (a > b) 10 else 20 -> Option A

4. Quick Check:

   Correct if-else assignment syntax is val x = if (cond) val1 else val2 [OK]

Hint: Remember: if-else expression is inside assignment with = [OK]

Common Mistakes:

• Using 'then' keyword which Kotlin does not have
• Misplacing equals signs around else
• Adding extra else after braces

3. What is the output of this Kotlin code?

val age = 18
val status = if (age >= 18) "Adult" else "Minor"
println(status)

medium

A. Minor

B. Adult

C. 18

D. Compilation error

Solution

1. Step 1: Check the condition age >= 18

   Since age is 18, the condition age >= 18 is true.

2. Step 2: Determine the assigned value to status

   Because the condition is true, status is assigned "Adult".

3. Final Answer:

   Adult -> Option B

4. Quick Check:

   Condition true assigns "Adult" [OK]

Hint: If condition true, if-else expression returns first value [OK]

Common Mistakes:

• Assuming >= 18 is false for 18
• Printing age instead of status
• Confusing syntax causing compile error

4. Identify the error in this Kotlin code:

val x = if (num > 0) "Positive"

medium

A. Incorrect variable declaration

B. Wrong comparison operator

C. Missing else branch in if-else expression

D. No error, code is correct

Solution

1. Step 1: Check if-else expression completeness

   An if-else expression used for assignment must have both if and else branches.

2. Step 2: Identify missing else branch

   The code only has if (num > 0) "Positive" but no else part, causing a syntax error.

3. Final Answer:

   Missing else branch in if-else expression -> Option C

4. Quick Check:

   If-else expression must include else [OK]

Hint: Always include else when assigning with if-else expression [OK]

Common Mistakes:

• Omitting else branch
• Thinking if alone can assign value
• Ignoring compiler error messages

5. You want to assign a grade based on score using if-else expression assignment in Kotlin. Which code correctly assigns "A" if score >= 90, "B" if score >= 80, else "C"?

hard

A. val grade = if (score >= 90) "A" else if score >= 80 "B" else "C"

B. val grade = if (score >= 90) "A" else (score >= 80) "B" else "C"

C. val grade = if (score >= 90) { "A" } else if (score >= 80) { "B" } else { "C" } else

D. val grade = if (score >= 90) "A" else if (score >= 80) "B" else "C"

Solution

1. Step 1: Understand nested if-else expression syntax

   Kotlin allows nested if-else expressions to assign values based on multiple conditions.

2. Step 2: Check each option for correct syntax and logic

   val grade = if (score >= 90) "A" else if (score >= 80) "B" else "C" correctly nests if-else expressions with proper syntax and covers all cases.

3. Final Answer:

   val grade = if (score >= 90) "A" else if (score >= 80) "B" else "C" -> Option D

4. Quick Check:

   Nested if-else expressions assign multiple conditions [OK]

Hint: Use nested if-else expressions for multiple conditions [OK]

Common Mistakes:

• Missing parentheses in nested if
• Incorrect else placement
• Adding extra else after braces