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Boolean and Char

Learn Boolean and Char types.

Boolean and Char

Boolean takes only two values: true and false. It is used in conditions (if, while) and logical expressions.

Char represents a single Unicode character and is written between single quotes: 'A', '7', '\n'. Char is not a number; to get a character's code you use the code property.

val active: Boolean = true
val letter: Char = 'K'
println(letter.code)   // 75

Practice Char code

Write a fun main(). Declare val letter: Char = 'K'. Print the character's code with println(letter.code).

Sample solution

Main.kt
fun main() {
    val letter: Char = 'K'
    println(letter.code)
}

Expected output

75

Char vs String

Char represents one character; String represents zero or more characters. 'A' is a Char; "A" is a String with one character. These are different types and behave differently in arithmetic.

Char + Char produces an Int; String + String concatenates. Mixing them creates compile errors or unexpected behavior.

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 How is a Char written?

  • "A"
  • A
  • 'A' Correct answer
  • (A)

Explanation: A Char is written between single quotes.

2 Boolean value

Question 
val active: Boolean = ____
Answer 
val active: Boolean = true

Explanation: Boolean values are true or false.

3 Boolean and Char: match the terms

Term Meaning
Boolean true/false
Char 'A'
Int 5
String "text"

All lessons in Beginner

1 Kotlin basics

  1. What is Kotlin?
  2. Your first program
  3. The main function
  4. Comments
  5. String templates
  6. Summary - Kotlin basics

2 Variables

  1. val and var
  2. Type inference
  3. const
  4. lateinit
  5. by lazy
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Boolean and Char
  4. String
  5. Any and Unit
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Elvis operator
  6. Summary - Operators

6 Strings

  1. Creating strings
  2. String templates
  3. String methods
  4. substring
  5. split and replace
  6. Summary - Strings

7 Conditionals

  1. The if statement
  2. else and else if
  3. if expression
  4. when
  5. when expression
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. Range
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding items
  3. Calculating totals
  4. Listing the cart
  5. Putting it together

10 Arrays

  1. Creating arrays
  2. Array access
  3. Array size
  4. Array loop
  5. Array methods
  6. Summary - Arrays

11 Lists

  1. Creating lists
  2. List operations
  3. List access
  4. List iteration
  5. List methods
  6. Summary - Lists

12 Maps and Sets

  1. Creating sets
  2. Set operations
  3. Creating maps
  4. Map operations
  5. Map iteration
  6. Summary - Maps and Sets

13 Functions

  1. Defining functions
  2. Return values
  3. Expression body
  4. Default parameters
  5. Named arguments
  6. Summary - Functions

14 Null safety

  1. Nullable types
  2. ?, !! and ?:
  3. let
  4. Null check
  5. lateinit
  6. Summary - Null safety

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string operations

  1. Regex
  2. matches and find
  3. replace
  4. StringBuilder
  5. trim and pad
  6. Summary - Advanced strings

17 Enums

  1. enum class
  2. Enum values
  3. Enum properties
  4. when with enum
  5. Enum and range
  6. Summary - Enums

18 Exceptions

  1. try/catch
  2. throw
  3. finally
  4. try expression
  5. Custom exceptions
  6. Summary - Exceptions

19 Class basics

  1. class
  2. Constructor
  3. Properties
  4. Methods
  5. this
  6. Summary - Class basics

20 Beginner final

  1. Project design
  2. Classes
  3. Collections
  4. Error handling
  5. Putting it together