Which of the following Kotlin expressions correctly uses the Elvis operator to assign a default value of 10 when num is null?

easy📝 Conceptual Q2 of 15

Kotlin - Null Safety

Which of the following Kotlin expressions correctly uses the Elvis operator to assign a default value of 10 when num is null?

Aval result = num ?: 10

Bval result = num ? 10

Cval result = num ?: "10"

Dval result = num ??: 10

Step-by-Step Solution

Solution:

Step 1: Review correct Elvis operator syntax
The Elvis operator is ?: and is used as variable ?: defaultValue.
Step 2: Check each option
val result = num ?: 10 uses ?: correctly with a numeric default. val result = num ? 10 uses a single question mark which is invalid. val result = num ?: "10" uses a string default which is a type mismatch if num is numeric. val result = num ??: 10 uses ??: which is invalid syntax.
Final Answer:
val result = num ?: 10 -> Option A
Quick Check:
Correct Elvis syntax = val result = num ?: 10 [OK]

Quick Trick: Use ?: with correct syntax and matching types [OK]

Common Mistakes:

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