CODEWITHSUNDEEP
rubyarrays
Mike F
Mike F

Reputation: 309

ruby array input

I am trying to write a small function with ruby that gets fed a array from the user and then sums up the data in the array. I have written it as

    def sum(a)
      total = 0
      a.collect { |a| a.to_i + total }
    end

The function then runs through a rspec, which tests it by initially feeding into it a blank array. This this causes the following error

    sum computes the sum of an empty array
    Failure/Error: sum([]).should == 0
    expected: 0
        got: [] (using ==)

So its telling me that when it feeds the blank array in, its supposed to get 0 but instead its getting the array. I tried putting in a if statement written as

    def sum(a)
      total = 0
      a.collect { |a| a.to_i + total }
      if total = [] then { total = 0 end }
    end

but it gives me an error saying 

    syntax error, unexpected '}', expecting => (SyntaxError)

what am I doing wrong?

Upvotes: 0

Views: 1692

Answers (3)

DigitalRoss
DigitalRoss

Reputation: 146073

gets.split.map(&:to_i).inject(:+)

Upvotes: 0

Sergio Tulentsev
Sergio Tulentsev

Reputation: 230336

You shouldn't use map/collect for this. reduce/inject is the appropriate method

def sum(a)
  a.reduce(:+)
  # or full form
  # a.reduce {|memo, el| memo + el }

  # or, if your elements can be strings
  # a.map(&:to_i).reduce(:+)
end

Upvotes: 2

000
000

Reputation: 27247

See here: How to sum array of numbers in Ruby?

and here: http://www.ruby-doc.org/core-1.9.3/Enumerable.html#method-i-inject

def sum(a)
    array.inject(0) {|sum,x| sum + x.to_i }
end

Upvotes: 0

Related Questions