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Summary - Operators

Combine arithmetic, logical and Elvis operators to build a grade calculator.

Summary - Operators

So far you've learned arithmetic, assignment, comparison, logical and Elvis operators. Each group serves a different purpose: arithmetic for calculations, assignment for changing values, comparison for conditions, logical for combining Booleans, Elvis for null handling.

These operators are the basic tools for writing calculations and conditions in code. Choosing the right operator makes code both shorter and more readable.

Practice Put it together

Write a fun main(). Declare val a = 10 and val b = 3. Print whether the remainder equals 1 with println(a % b == 1).

Sample solution

Main.kt
fun main() {
    val a = 10
    val b = 3
    println(a % b == 1)
}

Expected output

true

Next step

Congratulations! You've completed the operators group. You've learned all the fundamentals of the beginner level: program structure, variables, data types, the calculator project and operators.

In the next, intermediate level you'll focus on control flow, functions, classes and collections. With solid fundamentals, the intermediate level will feel much smoother.

Questions and answers

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

1 Which is a logical operator?

  • && Correct answer
  • +
  • %
  • ?:

Explanation: && is a logical operator.

2 Match the concepts

Term Meaning
+ Addition
== Equal
&& And
?: Elvis

3 Summary - Operators: fill in the missing part

Question 
val name = input ____ "Guest"
Answer 
val name = input ?: "Guest"

Explanation: With ?: you give a default for null values.

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