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The 'not' Operator

Part of the Fundamentals section of Coddy's Lua journey. Lesson 22 of 90.

not operator, which works differently from and and or. Instead of combining two conditions, the not operator inverts a single boolean value, flipping true to false and false to true.

Here's how the not operator works:

gameOver = false
gameRunning = not gameOver  -- gameRunning is true

playerAlive = true
playerDead = not playerAlive  -- playerDead is false

The not operator is particularly useful when you need to check the opposite of a condition. For example, instead of checking if a game is over, you might want to check if it's not over to continue playing.

isComplete = false
canContinue = not isComplete  -- canContinue is true

print(canContinue)  -- Output: true
challenge icon

Challenge

Easy

Check if a game is currently running by using the not operator to invert a game over status. Create a variable called gameOver and assign it the value false. Use the not operator to create a new variable called gameRunning that represents the opposite of the game over status. Print the result.

Try it yourself

-- TODO: Write your code here

-- Print the result
print(gameRunning)
quiz iconTest yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction

The LanguageHello World!Comments

4Operators 2 Relational & Logic

Equality OperatorsRelational OperatorsThe 'and' OperatorThe 'or' OperatorThe 'not' OperatorShort-Circuit EvaluationTruthy and Falsy ValuesRecap - Simple Logic

7Basic Conditional Logic

The if-then StatementThe if-then-else StatementThe elseif StatementRecap - Treasure Chest

10Tables Part 1: List-Style

What is a Table?Creating a TableAccessing Elements by IndexModifying Elements by IndexThe Length Operator '#'table.insert()table.remove()Recap - Manage Party Members

13Project: Simple Potion Shop

Project SetupAdding a PotionProject lessonDisplaying the InventoryProject lessonCalculating Total Stock ValueProject lessonFinding a Specific PotionProject lessonSelling a PotionProject lesson

2Variables and Data Types

What is a Variable?NumbersStringsBooleansThe Value 'nil'The type() FunctionNaming ConventionsRecap - Character Profile

5Basic Output

Printing LiteralsPrinting VariablesPrinting Multiple ValuesCombining Strings & VariablesThe tostring() FunctionInputCastRecap - Status ReportRecap - Till 120

8String Manipulation Basics

string.len()string.upper & string.lowerstring.sub()string.rep()string.find()Recap - Format Username

11Tables 2: Dictionary-Style

Key-Value PairsCreating Dictionary-Style TablAccessing - Bracket NotationAccessing with Dot NotationAdding and Modifying PairsRemoving Pairs with nilRecap - Item Properties

14Variable Scope

Global VariablesLocal VariablesWhy Use Local Variables?Scope and BlocksRecap - Scope Puzzle

3Operators 1 Arithmetic & Conc

Arithmetic OperatorsModulo OperatorExponentiation OperatorString ConcatenationOperator PrecedenceRecap - Simple Calculations

6Project: Character Stats Disp

Welcome MessageDeclare Character StatsProject lessonDisplay Basic StatsProject lessonAdd a Boolean FlagProject lessonFinal SummaryProject lesson

9Functions Basics

Declaring a FunctionCalling a FunctionFunctions with ParametersFunctions with Multiple ParamsThe 'return' StatementRecap - Area Calculator

12Loops Basics

The while LoopThe repeat-until LoopThe Numeric for Loopfor Loop with a StepThe 'break' StatementRecap - Countdown

15Final Challenges

Recap - Player TurnRecap - Simple DatabaseRecap - Sum of Even Numbers

Practice on your own: Online Lua compiler