CODEWITHSUNDEEP
rubywindows-7-x64
beegee Assem
beegee Assem

Reputation: 79

Why is my Ruby Code not processing the input?

STDIN.read.split("\n").each do |a|
a=gets.to_i
if a >=0
 puts "a is positive"

end
end

Output

C:\Ruby221-x64\programs>ruby test2.rb
5
test2.rb:3:in `read': Interrupt
    from test2.rb:3:in `<main>'

Question: Why is my Ruby Code not going into the if?

Also Is the above code a way to handle continuous input? how will my code know after which input to stop. I had to press Ctrl-C to come out

Upvotes: 0

Views: 75

Answers (3)

lurker
lurker

Reputation: 58244

Your gets call is superfluous because the STDIN.read.split("\n").each do |a| already reads the inputs into a. So remove the gets:

STDIN.read.split("\n").each do |a|
  if a.to_i >= 0
    puts "#{a} is positive"
  end
end

Note that the I/O is buffered, and you're operating on a block basis, so you'll get:

Enter these inputs:

5
4
3

Press Ctrl-D to end the input (for Linux) or Ctrl-Z (for Windows), then you'll get results:

5 is positive
4 is positive
3 is positive

 => ["5", "4", "3"]

If you want this to be more interactive, then don't use the STDIN... each construct, but just do a loop with gets.to_i. For example:

loop do
  a = gets
  break if a.nil?    # Exit loop on EOF (ctrl-D)

  if a.to_i > 0
    puts "a is positive"
  end
end

If I put this into a file, say foo.rb, then I get:

OS_Prompt> ruby foo.rb
3
a is positive
5
a is positive
2
a is positive
-1
-3
2
a is positive
[ctrl-D]
OS_Prompt>

And it will quit the loop on ctrl-D since that will cause gets to return nil. Although in Windows, it might want Ctrl-Z.

Upvotes: 3

Pardeep Dhingra
Pardeep Dhingra

Reputation: 3946

STDIN.read.split("\n").each do |a|

This line is already taking input continuously then whats the need of gets.

while(true)
   b= gets.chomp.to_i
   puts b >=0 ? "b is positive" : "b is negative"
end

Here chomp is used to remove \n from the input

Upvotes: 0

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

▶ loop do
▷   b = STDIN.gets.to_i
▷   break if b.zero?
▷   puts b > 0 ? 'positive' : 'negative'
▷ end
#⇒ 5
# positive
# -4
# negative
# 0
# => nil

Upvotes: 0

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