I am trying to get a number from the user, store this number in the array and then add everything in the array together to display a total.
names = Array.new(20)
sum = 0
x = 0
for index in 0..5
puts "Enter a number: "
data = gets.to_i
names.push data
x = x + names[index]
end
puts x
But I am getting the error rb:10:in `+': nil can't be coerced into Integer (TypeError)
I guess its not allowing me to add whatever is in the array together. Anybody know a workaround for this?
There are some issues with your code.
Array.new(20) – you probably think this creates an array of the given size. Well, it does, but it also fills the array with a default object of nil:
Array.new(3)
#=> [nil, nil, nil]
In Ruby, you just create an empty array. It will grow and shrink automatically. And instead of Array.new you can use an array literal:
names = []
for index in 0..5 – for loops are very unidiomatic. You should use one of these:
(0..5).each do |index|
# ...
end
0.upto(5) do |index|
# ...
end
6.times do |index|
# ...
end
And finally:
names.push data
x = x + names[index]
You are pushing an element to the end of the array and then fetch it from the array using an absolute index. This only works if index and array size correlate exactly.
It's more robust to either use an explicit index for both, storing and fetching:
names[index] = data
x = x + names[index]
or to fetch the last element: (note that index isn't needed)
names.push data
x = x + names.last
Ruby also provides negative indices that are relative to the array's end:
names.push data
x = x + names[-1]
Needless to say, you could just omit the fetching:
names.push data
x = x + data
It might be useful to separate the data gathering from the calculation:
numbers = []
6.times do
puts 'Enter a number: '
numbers << gets.to_i
end
and then:
numbers = [1, 2, 3, 4, 5, 6] # <- example input
numbers.sum
#=> 21
# -- or --
numbers.inject(:+)
#=> 21
# -- or --
sum = 0
numbers.each { |n| sum += n }
sum
#=> 21
You are initializing the array with 20 nil names. Then you push the first entered number to the array (position 21) and try to concat the position [0] (names[0]) that is nil.
Try to change the first line:
names = Array.new
x = x + data– there's no need to fetch the element from the array again.