Summing several numbers

gistfile1.rb

# these all accomplish the same goal.

def sum(numbers=[])
  sum = 0
  numbers.each { |i| sum += i }
  sum
end

def sum(numbers=[])
  numbers.inject(0) { |sum,element| sum += element }
end

# my favorite
def sum(numbers=[])
  numbers.inject(:+)
end

# this solution won't satisfy the spec for the exercise, but what if we didn't want to pass in an array?
# What if we wanted to allow a user to pass in an arbitrary set of numbers? Let's check out Ruby's SPLAT

def sum(*numbers)
  numbers.inject(:+)
end

# using splat, we can call sum like this:
sum(1,2,3,4,5)
# or
sum(1,2,3)
# rather than passing in array like this:
sum([1,2,3,4])

# I just wanted to introduce the splat, since I think it's pretty cool. More on this later.