.each vs. .length.times and TypeError

facebook_response_array_total.rb

#total sum of array .each vs. .length.times

#using .length.times
def total(array)
  sum = 0
  #The length method returns the size of the array. 
  #Here, adding .times iterates the following block length times...
  array.length.times do |x|
  #...since the use of .times passes the parameter, x,  0 through (length -1), 
  #the block needs to get the value the array elements via index.
  
  #your code reflects this
  #so this is why it works here
    sum += array[x] #works: add value at array index 0 through length-1 (i.e., all of them) to sum
  end
  sum
end


#using .each
def total(array)
  sum = 0
  #.each evaluates the block once for each element of the array
  array.each do | x | # here, the parameter, x, references the actual value of the array elements
  #so summing the total calls for simply adding x, and not the array value AT INDEX x
    sum += x
  end
  sum
end

So, to address the error you get when you use .each and parameter x , I believe getting a nil can't be coerced into Fixnum (TypeError) would result from attempting to add to the array the value at an index that is outside the array bounds (e.g., a 3-element array with one value of 6 would look to append the sum with the value of the array at index 6). When that happens, it tries to add nil to the Fixnum and gives you an error.

Anyone else have thoughts on this or know if this is on the right track for interpreting the error?

for readability, it might help to copy/paste the gist into Sublime to make the comments vs. code clearer.... :)

Hi Caroline.

Thanks for taking the time to put this together. After reading through your notes it makes sense.

• Michael

Another good exercise would be to follow through with ruby-docs to make sense of what's going on.

In your code, by introducing the right block onto the .times method, you were able to sum the elements with their indices in exactly the amount of times required. It's a pretty interesting chain method.