You want to use a when expression to categorize ages into groups: "Child" for 0-12, "Teen" for 13-19, "Adult" for 20-64, and "Senior" for 65 and above. Which when expression correctly implements this?
hard📝 Application Q15 of 15
Kotlin - Control Flow as Expressions
You want to use a when expression to categorize ages into groups: "Child" for 0-12, "Teen" for 13-19, "Adult" for 20-64, and "Senior" for 65 and above. Which when expression correctly implements this?
Awhen (age) {
in 0..12 -> "Child"
in 13..19 -> "Teen"
in 20..64 -> "Adult"
else -> "Senior"
}
Bwhen {
age >= 0 && age <= 12 -> "Child"
age >= 13 && age <= 19 -> "Teen"
age >= 20 && age <= 64 -> "Adult"
age >= 65 -> "Senior"
else -> "Unknown"
}
Dwhen (age) {
in 0..12 -> "Child"
in 13..19 -> "Teen"
in 20..64 -> "Adult"
in 65..100 -> "Senior"
else -> "Unknown"
}
Step-by-Step Solution
Solution:
Step 1: Understand when with condition checks
when {
age >= 0 && age <= 12 -> "Child"
age >= 13 && age <= 19 -> "Teen"
age >= 20 && age <= 64 -> "Adult"
age >= 65 -> "Senior"
else -> "Unknown"
} uses when without argument and checks conditions with boolean expressions, which is valid and flexible.
Step 2: Check other options for correctness
when (age) {
in 0..12 -> "Child"
in 13..19 -> "Teen"
in 20..64 -> "Adult"
else -> "Senior"
} is valid but misses handling negative ages explicitly; when (age) {
0..12 -> "Child"
13..19 -> "Teen"
20..64 -> "Adult"
65 -> "Senior"
} uses invalid syntax for ranges; when (age) {
in 0..12 -> "Child"
in 13..19 -> "Teen"
in 20..64 -> "Adult"
in 65..100 -> "Senior"
else -> "Unknown"
} limits "Senior" to 65-100 and has an else for unknown ages.
Step 3: Choose the best option
when {
age >= 0 && age <= 12 -> "Child"
age >= 13 && age <= 19 -> "Teen"
age >= 20 && age <= 64 -> "Adult"
age >= 65 -> "Senior"
else -> "Unknown"
} covers all age ranges clearly with conditions and includes an else for unknown ages.
Final Answer:
when {
age >= 0 && age <= 12 -> "Child"
age >= 13 && age <= 19 -> "Teen"
age >= 20 && age <= 64 -> "Adult"
age >= 65 -> "Senior"
else -> "Unknown"
} -> Option B
Quick Check:
Use condition checks inside when for flexible ranges [OK]
Quick Trick:Use condition checks inside when for complex ranges [OK]
Common Mistakes:
MISTAKES
Using invalid range syntax without 'in'
Not handling unexpected values with else
Limiting ranges incorrectly or missing conditions
Master "Control Flow as Expressions" in Kotlin
9 interactive learning modes - each teaches the same concept differently
