Hey, I have just finished the chapter “Ordering your Library” so I want
to experiment a little more with arrays and sorting. I wrote some code
that gets the user’s input on how many cities he’d like to have
alphabetized, but I’m encountering some problems. Here’s the code:
def alphabetize(arr, rev = false)
if rev == true
arr.sort!
arr.reverse!
else
arr.sort! {|item1, item2| item1 <=> item2}
end
arr.each {|thing| puts “#{thing}” + " "}
end
puts “How many cities would you like to specify?”
n = gets.chomp.to_i
for i in 0…n
puts (i+1).to_s + ". city: "
cities = Array.new(n)
cities[i] = gets.chomp
end
alphabetize(cities)
So basically the user says how many cities he wants to sort and then
specifies which ones. Reading the user’s input works just fine, but
apparently, there’s some problem when the method is being called, since
I keep getting this error:
comparison of NilClass with String failed
It has to be something in the method, right? I’m not that experienced
with Ruby yet, so I’m kind of stuck here and I can’t think of a
solution. Any help would be greatly appreciated!
The simplest thing to start with would be to feed a list into the
function
and see if that works:
cities = %w{london paris bejing tokyo moscow}
alphabetize(cities)
This gives me
bejing
london
moscow
paris
tokyo
So the sort function seems ok. The real problem is this
puts “How many cities would you like to specify?”
n = gets.chomp.to_i
for i in 0…n
puts (i+1).to_s + ". city: "
cities = Array.new(n)
cities[i] = gets.chomp
end
Basically you delete the array every time you go round the loop.
puts “How many cities would you like to specify?”
n = gets.chomp.to_i
cities = Array.new
n.times.each do
puts "City: "
cities << gets.chomp
end
The creation of the array is outside the loop and do things in a more
Ruby
way
On Sun, Nov 24, 2013 at 8:27 PM, Peter H.
[email protected] wrote:
The creation of the array is outside the loop and do things in a more Ruby
way
You could even do
puts “How many cities would you like to specify?”
n = Integer(gets)
cities = Array.new n do
puts "City: "
gets.chomp
end
Kind regards
robert
Robert, clever!!! 
On Mon, Nov 25, 2013 at 7:07 AM, Robert K.
Peter H. wrote in post #1128490:
n.times.each do
You probably already know this, but “.each” is redundant.