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string.len()

Part of the Fundamentals section of Coddy's Lua journey. Lesson 44 of 90.

The string.len() function is your first tool for working with text data in more sophisticated ways.

The string.len() function returns the number of characters in a string. This includes letters, numbers, spaces, and any special characters. Here's the basic syntax:

string.len(your_string)

Here's a simple example:

local username = "player123"
local length = string.len(username)
print(length)  -- outputs: 9

The string "player123" contains 9 characters, so string.len() returns 9.

challenge icon

Challenge

Easy

Create a username validation system that checks if a username meets the minimum length requirement. Declare a variable called username and assign it the value "player123". Use the string.len() function to find the length of the username, then store this length in a variable called usernameLength. Finally, print the length value.

Try it yourself

-- Declare the username variable
local username = "player123"

-- TODO: Write your code here to find the length and store it in usernameLength

-- Print the length
print(usernameLength)
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