String to number conversion in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What Kotlin function converts a String to an Int?

The toInt() function converts a String to an Int in Kotlin.

intermediate

How do you safely convert a String to a number in Kotlin without risking an exception?

Use toIntOrNull() or toDoubleOrNull(). They return null if conversion fails, avoiding exceptions.

beginner

What happens if you call toInt() on a String that is not a valid number?

Kotlin throws a NumberFormatException if the String cannot be converted to an Int.

beginner

Which Kotlin function converts a String to a Double?

The toDouble() function converts a String to a Double in Kotlin.

beginner

How can you convert a String to a Long in Kotlin?

Use the toLong() function to convert a String to a Long number.

Which Kotlin function converts a String to an Int and throws an exception if invalid?

A parseInt()

B toIntOrNull()

C toInt()

D convertToInt()

toInt() converts a String to Int but throws NumberFormatException if the String is invalid.

What does toIntOrNull() return if the String is not a valid number?

A null

B 0

C Exception

D Empty String

toIntOrNull() returns null when the String cannot be converted safely.

Which function converts a String to a Double in Kotlin?

A toDouble()

B toFloat()

C toDecimal()

D toNumber()

toDouble() converts a String to a Double number.

If you want to avoid exceptions during conversion, which function should you use?

A toInt()

B toString()

C toLong()

D toIntOrNull()

toIntOrNull() safely converts or returns null without throwing exceptions.

What exception is thrown by toInt() if conversion fails?

A IllegalArgumentException

B NumberFormatException

C NullPointerException

D ClassCastException

toInt() throws NumberFormatException when the String is not a valid number.

Explain how to convert a String to an Int safely in Kotlin and handle invalid input.

Think about functions that return null instead of throwing errors.

Describe the difference between toInt() and toIntOrNull() in Kotlin.

One throws an error, the other returns null on failure.