Basic Data Structures in Ruby - Stack

The Stack data structure is described in detail over here : Data Structures: Stacks ( with C Program source code) .

Ruby doesn't provide an explicit 'stack' but for all practical purposes, the Array provided by Ruby can be treated as a full-fledged stack.

# Based on the ideas from : http://macdevelopertips.com/ruby/using-a-stack-with-ruby.html
# Stacks are a Last In First Out Data Structure
class Stack
  def initialize
  @elements = []
  end

  def length
  @elements.length
  end

  # Return self
  def push(x)
  @elements.push x
  self
  end

  def pop
  @elements.pop
  end

  def peek
  @elements[-1]
  end

  def display
  puts "(LeftMost : Oldest Element) " + @elements.join("<-") +" (RightMost : Newest Element)"
  end
end

testStack = Stack.new()
# Display initial (empty stack)
testStack.display
testStack.push(3).push(5).push(10)
# Now display stack
testStack.display
# Check the value at the top of the head
popped = testStack.pop
puts "Popped the value : " + popped.to_s
# Now the stack is ...
testStack.display
popped = testStack.pop
puts "Popped the value : " + popped.to_s
# Now the stack is ...
testStack.display

=begin

Sample Output :
~/work/ruby_tutorials$ ruby stack.rb
(LeftMost : Oldest Element) (RightMost : Newest Element)
(LeftMost : Oldest Element) 3<-5<-10 (RightMost : Newest Element)
Popped the value : 10
(LeftMost : Oldest Element) 3<-5 (RightMost : Newest Element)
Popped the value : 5
(LeftMost : Oldest Element) 3 (RightMost : Newest Element)
=end

Check out some of our other Ruby Tutorials :

Introduction to Ruby

Introduction to Ruby and some playing around with the Interactive Ruby Shell (irb) Introduction to Ruby - Conditional statements and Modifiers: If-then, Unless, Case Introduction to Ruby Comments - Single and Multi-Line comments Introduction to Ruby Loops - Using While, Until, For, Break, Next , Redo, Retry
Introduction to Ruby - Arrays - Sorting, Filtering (Select), Transforming, Multi-Dimensional Arrays Introduction to Ruby - Strings Introduction to Ruby - Making a Script Executable Introduction to Ruby - Regular Expressions, Match, Scan
Introduction to Ruby - Computing Factorials Recursively : An Example of Recursion Introduction to Ruby - Binomial Coefficients (nCr) : An Example of Recursion Introduction to Ruby - Computing a Power Set : An Example of Recursion Introduction to Ruby - Towers of Hanoi : An Example of Recursion
Introduction to Ruby - Strings: Substitution, Encoding, Built-In Methods

Basic Data Structures With Ruby

Basic Data Structures in Ruby - Insertion Sort Basic Data Structures in Ruby - Selection Sort Basic Data Structures in Ruby - Merge Sort Basic Data Structures in Ruby - Quick Sort Functional Programming with Ruby
Basic Data Structures in Ruby - Stack Basic Data Structures in Ruby - The Queue Basic Data Structures in Ruby - Linked List - ( A Simple, Singly Linked List) Basic Data Structures in Ruby - Binary Search Tree