If as an expression returning value in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean that if is an expression in Kotlin?

In Kotlin, if can return a value, so you can assign the result of an if expression directly to a variable.

beginner

How do you assign a value using if as an expression?

You write val result = if (condition) value1 else value2. The variable result gets the value from the branch that runs.

intermediate

Can if expression in Kotlin have no else branch?

No, if you use if as an expression to return a value, you must include an else branch to cover all cases.

intermediate

What type does an if expression return?

The if expression returns a value of the common supertype of all branches. For example, if one branch returns Int and another Double, the result type will be Double.

beginner

Show a simple Kotlin example using if as an expression.

Example:<br>

val max = if (a > b) a else b

<br>This assigns the greater of a or b to max.

In Kotlin, what must you include when using if as an expression to assign a value?

A An else branch

B Only the if branch

C A loop

D A return statement

When using if as an expression, Kotlin requires an else branch to ensure a value is always returned.

What does this Kotlin code return?<br>

val result = if (x > 0) "Positive" else "Non-positive"

A A Boolean value

B No value

C An Int value

D A String value

The if expression returns a String depending on the condition.

Which of these is a valid use of if as an expression in Kotlin?

A if (a > b) a else b

B val x = if (a > b) a

C val x = if (a > b) a else b

D if (a > b) { a }

Option C includes both if and else branches, making it a valid expression that returns a value.

What type will Kotlin infer for this expression?<br>

val x = if (flag) 10.0 else 20.5

A Int

B Double

C String

D Boolean

Kotlin infers the common supertype, which is Double because both 10.0 and 20.5 are Doubles.

Why is if as an expression useful in Kotlin?

A It allows assigning values directly from conditions.

B It replaces loops.

C It is faster than statements.

D It can only be used with numbers.

If as an expression lets you write cleaner code by assigning values directly based on conditions.

Explain how if as an expression works in Kotlin and why it requires an else branch.

Think about how Kotlin needs a value no matter what condition happens.

Write a Kotlin example using if as an expression to assign the smaller of two numbers to a variable.

Use <code>if (a < b) a else b</code> pattern.