Best ruby cheat sheet

def greeting(hello, *names) # *name is a splat argument, takes several parameters passed in an array
  return "#{hello}, #{names}"
end

start = greeting("Hi", "Justin", "Maria", "Herbert") # call a method by name

def name(variable=default)
  ### The last line in here get's returned by default
end

Source: github.com

Best ruby cheat sheet

unless false # unless checks if the statement is false (opposite to if).
puts “I’m here”
else
puts “not here”
end
# or
puts "not printed" unless true

Source: github.com

Best ruby cheat sheet

hashes.each do |x,y|
  print "#{x}: #{y}"
end

Source: github.com

Best ruby cheat sheet

10.times do
  print “this text will appear 10 times”
end

Source: github.com

Best ruby cheat sheet

# single line comment

Source: github.com

Best ruby cheat sheet

gets # is the Ruby equivalent to prompt in javascript (method that gets input from the user)
gets.chomp # removes extra line created after gets (usually used like this)

Source: github.com

Best ruby cheat sheet

"Hello".length # 5
"Hello".reverse # “olleH”
"Hello".upcase # “HELLO”
"Hello".downcase # “hello”
"hello".capitalize # “Hello”
"Hello".include? "i" # equals to false because there is no i in Hello
"Hello".gsub!(/e/, "o") # Hollo
"1".to_i # transform string to integer –– 1
"test".to_sym # converts to :test
"test".intern # :test
:test.to_s # converts to "test"

Source: github.com

Best ruby cheat sheet

i = 0
loop do
  i += 1
  print "I'm currently number #{i}” # a way to have ruby code in a string
  break if i > 5
end

Source: github.com

Best ruby cheat sheet

my_array = [a,b,c,d,e]
my_array[1] # b
my_array[2..-1] # c , d , e
multi_d = [[0,1],[0,1]]
[1, 2, 3] << 4 # [1, 2, 3, 4] same as [1, 2, 3].push(4)

Source: github.com

Best ruby cheat sheet

lambda { |param| block }
multiply = lambda { |x| x * 3 }
y = [1, 2].collect(&multiply) # 3 , 6

Source: github.com

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