Var for mutable references in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

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What does var mean in Kotlin?

var declares a variable whose value can change (mutable).

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How do you declare a variable that cannot change in Kotlin?

Use val to declare an immutable (read-only) variable.

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What happens if you try to reassign a val variable?

Kotlin will give a compile error because val variables cannot be reassigned.

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Example: <br>var count = 5<br>count = 10<br>What is the value of count after reassignment?

The value of count is 10 because var allows changing the value.

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Why use var instead of val?

Use var when you need to change the value later, like a counter or user input.

Which keyword declares a mutable variable in Kotlin?

A const

B val

C var

D let

var declares a mutable variable that can be reassigned.

What happens if you try to assign a new value to a val variable?

A Compile-time error

B It works fine

C Runtime error

D Value changes silently

val variables cannot be reassigned; Kotlin gives a compile-time error.

Which of these is a correct way to declare a mutable integer variable with initial value 3?

A const number = 3

B val number = 3

C let number = 3

D var number = 3

var number = 3 declares a mutable variable with value 3.

If you want a variable that never changes, which keyword do you use?

A var

B val

C mutable

D const

val declares an immutable variable that cannot be reassigned.

What is the main difference between var and val?

A <code>var</code> is mutable; <code>val</code> is immutable

B <code>var</code> is immutable; <code>val</code> is mutable

C Both are mutable

D Both are immutable

var allows changing the value; val does not.

Explain the difference between var and val in Kotlin.

Think about whether the variable's value can change after you set it.

Give an example where you would use var instead of val.

Think about situations where the value needs to update.