diff options
Diffstat (limited to 'ruby.html.markdown')
| -rw-r--r-- | ruby.html.markdown | 121 |
1 files changed, 109 insertions, 12 deletions
diff --git a/ruby.html.markdown b/ruby.html.markdown index 7cf5bdc7..e0a6bb6e 100644 --- a/ruby.html.markdown +++ b/ruby.html.markdown @@ -11,7 +11,10 @@ contributors: - ["Ariel Krakowski", "http://www.learneroo.com"] - ["Dzianis Dashkevich", "https://github.com/dskecse"] - ["Levi Bostian", "https://github.com/levibostian"] - + - ["Rahil Momin", "https://github.com/iamrahil"] + - ["Gabriel Halley", "https://github.com/ghalley"] + - ["Persa Zula", "http://persazula.com"] + - ["Jake Faris", "https://github.com/farisj"] --- ```ruby @@ -38,6 +41,12 @@ You shouldn't either 10 * 2 #=> 20 35 / 5 #=> 7 2**5 #=> 32 +5 % 3 #=> 2 + +# Bitwise operators +3 & 5 #=> 1 +3 | 5 #=> 7 +3 ^ 5 #=> 6 # Arithmetic is just syntactic sugar # for calling a method on an object @@ -45,7 +54,7 @@ You shouldn't either 10.* 5 #=> 50 # Special values are objects -nil # Nothing to see here +nil # equivalent to null in other languages true # truth false # falsehood @@ -60,8 +69,6 @@ false.class #=> FalseClass # Inequality 1 != 1 #=> false 2 != 1 #=> true -!true #=> false -!false #=> true # apart from false itself, nil is the only other 'falsey' value @@ -75,6 +82,26 @@ false.class #=> FalseClass 2 <= 2 #=> true 2 >= 2 #=> true +# Combined comparison operator +1 <=> 10 #=> -1 +10 <=> 1 #=> 1 +1 <=> 1 #=> 0 + +# Logical operators +true && false #=> false +true || false #=> true +!true #=> false + +# There are alternate versions of the logical operators with much lower +# precedence. These are meant to be used as flow-control constructs to chain +# statements together until one of them returns true or false. + +# `do_something_else` only called if `do_something` succeeds. +do_something() and do_something_else() +# `log_error` only called if `do_something` fails. +do_something() or log_error() + + # Strings are objects 'I am a string'.class #=> String @@ -92,8 +119,20 @@ placeholder = 'use string interpolation' 'hello ' + 3 #=> TypeError: can't convert Fixnum into String 'hello ' + 3.to_s #=> "hello 3" -# print to the output +# Combine strings and operators +'hello ' * 3 #=> "hello hello hello " + +# Append to string +'hello' << ' world' #=> "hello world" + +# print to the output with a newline at the end puts "I'm printing!" +#=> I'm printing! +#=> nil + +# print to the output without a newline +print "I'm printing!" +#=> I'm printing! => nil # Variables x = 25 #=> 25 @@ -140,6 +179,7 @@ array = [1, 2, 3, 4, 5] #=> [1, 2, 3, 4, 5] # Arrays can be indexed # From the front array[0] #=> 1 +array.first #=> 1 array[12] #=> nil # Like arithmetic, [var] access @@ -150,17 +190,27 @@ array.[] 12 #=> nil # From the end array[-1] #=> 5 +array.last #=> 5 # With a start index and length array[2, 3] #=> [3, 4, 5] +# Reverse an Array +a=[1,2,3] +a.reverse! #=> [3,2,1] + # Or with a range array[1..3] #=> [2, 3, 4] # Add to an array like this array << 6 #=> [1, 2, 3, 4, 5, 6] +# Or like this +array.push(6) #=> [1, 2, 3, 4, 5, 6] -# Hashes are Ruby's primary dictionary with keys/value pairs. +# Check if an item exists in an array +array.include?(1) #=> true + +# Hashes are Ruby's primary dictionary with key/value pairs. # Hashes are denoted with curly braces: hash = { 'color' => 'green', 'number' => 5 } @@ -179,6 +229,10 @@ new_hash = { defcon: 3, action: true } new_hash.keys #=> [:defcon, :action] +# Check existence of keys and values in hash +new_hash.key?(:defcon) #=> true +new_hash.value?(3) #=> true + # Tip: Both Arrays and Hashes are Enumerable # They share a lot of useful methods such as each, map, count, and more @@ -231,6 +285,12 @@ hash.each do |key, value| puts "#{key} is #{value}" end +# If you still need an index you can use "each_with_index" and define an index +# variable +array.each_with_index do |element, index| + puts "#{element} is number #{index} in the array" +end + counter = 1 while counter <= 5 do puts "iteration #{counter}" @@ -242,6 +302,19 @@ end #=> iteration 4 #=> iteration 5 +# There are a bunch of other helpful looping functions in Ruby, +# for example "map", "reduce", "inject", the list goes on. Map, +# for instance, takes the array it's looping over, does something +# to it as defined in your block, and returns an entirely new array. +array = [1,2,3,4,5] +doubled = array.map do |element| + element * 2 +end +puts doubled +#=> [2,4,6,8,10] +puts array +#=> [1,2,3,4,5] + grade = 'B' case grade @@ -280,19 +353,19 @@ rescue NoMemoryError => exception_variable puts 'NoMemoryError was raised', exception_variable rescue RuntimeError => other_exception_variable puts 'RuntimeError was raised now' -else +else puts 'This runs if no exceptions were thrown at all' -ensure +ensure puts 'This code always runs no matter what' end -# Functions +# Methods def double(x) x * 2 end -# Functions (and all blocks) implicitly return the value of the last statement +# Methods (and all blocks) implicitly return the value of the last statement double(2) #=> 4 # Parentheses are optional where the result is unambiguous @@ -326,7 +399,7 @@ surround { puts 'hello world' } # } -# You can pass a block to a function +# You can pass a block to a method # "&" marks a reference to a passed block def guests(&block) block.call 'some_argument' @@ -338,6 +411,28 @@ def guests(*array) array.each { |guest| puts guest } end +# If a method returns an array, you can use destructuring assignment +def foods + ['pancake', 'sandwich', 'quesadilla'] +end +breakfast, lunch, dinner = foods +breakfast #=> 'pancake' +dinner #=> 'quesadilla' + +# By convention, all methods that return booleans end with a question mark +5.even? # false +5.odd? # true + +# And if a method ends with an exclamation mark, it does something destructive +# like mutate the receiver. Many methods have a ! version to make a change, and +# a non-! version to just return a new changed version +company_name = "Dunder Mifflin" +company_name.upcase #=> "DUNDER MIFFLIN" +company_name #=> "Dunder Mifflin" +company_name.upcase! # we're mutating company_name this time! +company_name #=> "DUNDER MIFFLIN" + + # Define a class with the class keyword class Human @@ -516,7 +611,9 @@ Something.new.qux # => 'qux' ## Additional resources - [Learn Ruby by Example with Challenges](http://www.learneroo.com/modules/61/nodes/338) - A variant of this reference with in-browser challenges. -- [Official Documentation](http://www.ruby-doc.org/core-2.1.1/) +- [An Interactive Tutorial for Ruby](https://rubymonk.com/) - Learn Ruby through a series of interactive tutorials. +- [Official Documentation](http://ruby-doc.org/core) - [Ruby from other languages](https://www.ruby-lang.org/en/documentation/ruby-from-other-languages/) - [Programming Ruby](http://www.amazon.com/Programming-Ruby-1-9-2-0-Programmers/dp/1937785491/) - An older [free edition](http://ruby-doc.com/docs/ProgrammingRuby/) is available online. - [Ruby Style Guide](https://github.com/bbatsov/ruby-style-guide) - A community-driven Ruby coding style guide. +- [Try Ruby](http://tryruby.org) - Learn the basic of Ruby programming language, interactive in the browser. |