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Phase 0 Projects

Ruby Cheat Sheet

November 22nd, 2015

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As one of my final Phase 0 challenges, I've created a cheat sheet of commonly used methods in Ruby. All of the source data for these method can originally be found from the Ruby Docs . I originally intended to list a bunch more here, and may revise this cheat sheet if I have more time next week.

Array Methods Index

#each

Calls the given block once for each element in self, passing that element as a parameter.

 
          a = [ "a", "b", "c" ]
          a.each {|x| puts x + " - test " }
          =>  a - test
              b - test
              c - test
         

#eachSlice

Iterates the given block for each slice of elements. If no block is given, returns an enumerator.

 
          (1..10).each_slice(3) { |a| p a }
          # outputs below
          [1, 2, 3]
          [4, 5, 6]
          [7, 8, 9]
          [10]
         

#map

Invokes the given block once for each element of self. Creates and returns a new array containing the values returned by the block, but does not modify original array. Use map! to modify the original array.

 
        a = [ "a", "b", "c", "d" ]
        a.collect { |x| x + "!" }        #=> ["a!", "b!", "c!", "d!"]
        a.map.with_index{ |x, i| x * i } #=> ["", "b", "cc", "ddd"]
        a                                #=> ["a", "b", "c", "d"]
         

#length

Returns the number of elements in self. May be zero.

 
          [ 1, 2, 3, 4, 5 ].length   #=> 5
          [].length                  #=> 0