Ruby -- If Elsif Else Error
I'm getting an error here with a simple if else chain, and I can't figure out what is going on. I started learning ruby the other day, I already know some java, and was just trying to re-write programs to learn ruby faster. I am trying to tally vowels and consonants. Anyways here is my code...
#!/usr/bin/ruby/
alphabet = 'abcdefghijklmnopqrstuvwxyz'
array = alphabet.chars.to_a
vowel = 0
cons = 0
puts array.at(1)
for i in 0...26
if array.at(i) == "a"
vowel++
elsif array.at(i) == 'e'
vowel++
elsif array.at(i) == 'i'
vowel++
elsif array.at(i) == 'o'
vowel++
elsif array.at(i) == 'u'
vowel++
else
cons++
end#end if else chain
end#end for loop
puts 'Vowel: ' + vowel.to_s
puts 'Consonants: ' + cons.to_s
Here is the error I am getting:
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:11: syntax error, unexpected keyword_elsif elsif array.at(i) == 'e' ^
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:13: syntax error, unexpected keyword_elsif elsif array.at(i) == 'i' ^
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:15: syntax error, unexpected keyword_elsif elsif array.at(i) == 'o' ^
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:17: syntax error, unexpected keyword_elsif elsif array.at(i) == 'u' 开发者_如何学Go ^
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:19: syntax error, unexpected keyword_else
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:21: syntax error, unexpected keyword_end
C:/Users/Kelan/Documents/Programming/Ruby Files/Little Programs/Alphabet.rb:25: syntax error, unexpected $end, expecting keyword_end puts 'Consonants: ' + cons.to_s ^
[Finished in 0.203 seconds]
I'm sure it's just something silly, but I've been looking forever online for help and I have heard of your great community, so I thought I would try here,
Kelan
There is no ++ operator in Ruby. You should have used += 1
You may also want to learn about case
statement:
alphabet = 'abcdefghijklmnopqrstuvwxyz'
26.times do |i|
case alphabet[i]
when 'a' then vowel += 1
when 'e' then vowel += 1
when 'i' then vowel += 1
when 'o' then vowel += 1
when 'u' then vowel += 1
else cons += 1
end#end case
end#end times
puts 'Vowel: ' + vowel.to_s
puts 'Consonants: ' + cons.to_s
Or, even better, use method count
from class String
, like this:
alphabet = 'abcdefghijklmnopqrstuvwxyz'
vowels = 'aeiou'
vowel_count = alphabet.count vowels
cons_count = alphabet.length - vowel_count
puts "Vowels: #{vowel_count}"
puts "Consonants: #{cons_count}"
Your problem is you're using the Java/PHP/C style increment operator. Ruby isn't down with that. You have to use foo += 1
instead.
How about I show you a more Ruby way of doing this though?
# use a range to define your alphabet
alphabet = ('a'..'z').entries #=> ['a', 'b', 'c', ...]
# define vowels as members of an array. it's more flexible, which
# is great for things that change (what if you decide to use 'y'?)
vowels = %w{ a e i o u } #=> ['a', 'e', 'i', 'o', 'u']
# keep counts all together in a hash, which I personally find cleaner
counts = { :vowels => 0, :consonants => 0 }
# even the `for` loops in ruby use the iterators, so you actually
# get better performance out of using the more user-friendly `.each`
alphabet.each do |letter|
if vowels.include? letter
counts[:vowels] += 1
else
counts[:consonants] += 1
end
end
puts "There were #{counts[:vowels]} vowels and #{counts[:consonants]} consonants."
I think rather than vowel++
and con++
, you need to use vowel+=1
and con+=1
.
Ruby does not have C-style pre/post incrementors.
Here is yet another way to write the demo:
puts("%d vowels & %d consonants" % ('a'..'z').inject([0,0]) do |m, e|
m[/[aeiou]/.match(e) ? 0:1] += 1; m
end)
- There is an easy way of constructing the set of alphabets, using
Range
. - Since you are using ruby, you should use internal iterators instead of the external ones. You will rarely see a
for
loop in a good program in ruby. case
construction is handy in this case. You can put multiple matching patterns into one, separated by comma.- There is no
++
or--
operators in ruby. Use+= 1
. - Use
"#{ }"
notation. It's much better and faster than using+
. In fact, you can omitto_s
if you use it.
I would go like this:
vowel = 0
cons = 0
('a'..'z').each do |c|
case c
when 'a', 'e', 'i', 'o', 'u'; vowel += 1
else cons += 1
end
end
puts "Vowel: #{vowel}"
puts "Consonants: #{cons}"
If I wanted a shorter one, I might go with this:
partition = ('a'..'z').group_by{|c| c =~ /[aeiou]/}
puts "Vowel: #{partition[0].length}"
puts "Consonants: #{partition[nil].length}"
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