- 01Getting Started
- 02Your First Output (puts)
- 03Working with Variables
- 04Conditionals (if statements)
- 05Loops
- 06Writing a Method (Function)
- 07Working with Arrays
- 08Loops (while statements)
- 09Classes (Object-Oriented Programming)
- 10Error Handling (begin...rescue)
- 11Handy Array Methods
- 12Recursive Functions
- 13Using the Standard Library
- 14The case/when Statement
- 15The Ternary Operator
- 16Inheritance (Extending a Class)
- 17Writing Comments
- 18Logical Operators (AND, OR, NOT)
- 19Constants (names starting with a capital)
- 20Splitting and Joining Strings (split, join)
- 21Writing nil-Safe Code
- 22Searching an Array (include?)
- 23Transforming an Array (map)
- 24Two-Dimensional Arrays (Tabular Data)
- 25Writing a Custom Exception Class
- 26Default Parameter Values
- 27Working with Set
- 28Testing with Your Own assert Method
- 29Higher-Order Functions (Passing a Block)
- 30Stacks and Queues (Basic Data Structures)
- 31Type Conversion (Casting) Basics
- 32Intro to Regular Expressions (Pattern Matching)
- 33The Binary Search Algorithm
- 34Building a Caesar Cipher (a Character-Shifting Cipher)
- 35Understanding How Bubble Sort Works
- 36Building and Displaying Dates (Basic Year/Month/Day Operations)
- 37Writing Multiple Test Cases Together
- 38Speeding Up Calculations with Memoization (Caching)
- 39Normalizing Strings (strip, Unifying Case)
- 40Shallow Copy vs. Deep Copy
- 41Enum Basics
- 42Flattening an Array
- 43Reversing a String and Checking for Palindromes
- 44Pairing Up Two Arrays (the zip operation)
- 45Rounding Numbers (floor, ceil, round)
- 46Multi-Line Strings (Heredoc)
- 47Methods That Return Multiple Values
- 48Finding the GCD and LCM
- 49Formatting Numbers (Padding Digits, Decimal Places)
- 50Cleanup Logic with begin/rescue/ensure
- 51Methods That Work with Any Type
- 52File Reading and Writing Basics
- 53Generating Random Numbers
- 54Bitwise Operators (AND, OR, XOR, shifts)
- 55Reading Command-Line Arguments
- 56Waiting for a Fixed Amount of Time (sleep)
- 57Watch Out for Floating-Point Rounding Errors
- 58Reading from Standard Input
- 59FizzBuzz (the Classic Practice Problem)
- 60Checking Whether a Number Is Prime
- 61Set Operations with Set (Union, Intersection, Difference)
- 62Converting Number Bases (Binary, Hex)
- 63Checking Balanced Parentheses (an Application of Stacks)
- 64Checking Whether Two Words Are Anagrams
- 65Checking Whether a Year Is a Leap Year
- 66Converting Temperature (Celsius to Fahrenheit)
- 67Prime Factorization
- 68[Applied] Build a Simple Inventory Management Tool
Generating Random Numbers
In this lesson you will learn to generate random values with rand and Array#sample so you can build things like dice and raffles. This is for anyone searching for "Ruby random number generation".
rand() and Array#sample give you a random number, or a randomly chosen value from an array. Use them for dice rolls and raffles. The result changes every time you run it.
The sample code rolls a die from 1 to 6 with rand(1..6) and picks one of Rock, Scissors, and Paper with choices.sample. Notice how intuitively you can pass a range (1..6) straight to rand().
A common stumbling block for beginners is the difference between rand(6) and rand(1..6). Without a range, rand(6) returns 0 to 5, so the range form is the accurate way to get a die roll from 1 to 6.
The standard library also provides SecureRandom for randomness that is harder to predict. Random values are used widely, from shuffling in a game to sampling in a simulation.
๐งช This site can't compile or run Ruby directly, so it checks on the spot whether what you typed matches the reference code (scoring happens entirely in your browser โ nothing is sent anywhere).