Char type and Unicode behavior in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Kotlin Char type used for?

The Char type in Kotlin represents a single character, such as a letter, digit, or symbol. It holds a 16-bit Unicode character.

intermediate

How does Kotlin store characters internally in the Char type?

Kotlin stores Char as a 16-bit value representing a UTF-16 code unit, which can represent most common Unicode characters directly.

intermediate

What happens when a Unicode character requires more than 16 bits in Kotlin's Char type?

Characters outside the Basic Multilingual Plane (BMP) need two Char values called a surrogate pair to represent one Unicode character in Kotlin.

beginner

How can you represent a Unicode character in Kotlin using escape sequences?

You can use the syntax \uXXXX where XXXX is the 4-digit hexadecimal Unicode code unit for the character, e.g., '\u0041' for 'A'.

intermediate

Why might a Kotlin String have a different length than the number of Unicode characters it displays?

Because Kotlin String length counts Char units (UTF-16 code units), some characters (like emojis) use two Char units, so length can be greater than visible characters.

What Kotlin type is used to store a single Unicode character?

A Char

B String

C Int

D Byte

The Char type stores a single Unicode character in Kotlin.

How many bits does a Kotlin Char use internally?

A 32 bits

B 8 bits

C 16 bits

D 64 bits

Kotlin Char uses 16 bits internally, representing a UTF-16 code unit.

What is a surrogate pair in Kotlin's Unicode handling?

A A pair of integers

B Two <code>Char</code> values representing one Unicode character outside BMP

C A pair of strings

D A Kotlin keyword

Surrogate pairs are two Char values used to represent one Unicode character outside the Basic Multilingual Plane.

How do you write the Unicode character 'A' using an escape sequence in Kotlin?

A '\u0041'

B '\x41'

C '\u41'

D '\U0041'

The correct Unicode escape sequence in Kotlin is \u0041 for 'A'.

Why might string.length be larger than the number of visible characters?

A Because of string encoding errors

B Because Kotlin counts words, not characters

C Because of trailing spaces

D Because some characters use two <code>Char</code> units (surrogate pairs)

Some Unicode characters like emojis use two Char units, so length counts code units, not visible characters.

Explain how Kotlin's Char type represents Unicode characters and what happens with characters outside the Basic Multilingual Plane.

Think about how UTF-16 encoding works with Kotlin's Char.

Describe how to use Unicode escape sequences in Kotlin to represent characters and why string length might not match visible characters.

Consider how Kotlin counts characters internally versus what you see.