I can't get this to work with the Start Command Prompt with Ruby on windows.
I got this simple programm:
puts "Whats your name?"
name = gets
puts "Hello" + name + ". How are you?"
But if I call it with "ruby program.rb", instead for waiting for my input, it just prints out:
Whats your name?
Helloputs "Whats your name?"
. How are you?
It is like the "gets" command is not been recognized. Why does this happen?
It looks like you are (somehow) passing the name of your programm two times on the command line. Your described behavior is reproducible when you are running
ruby program.rb program.rb
This works the way it does since gets does not read from STDIN in all cases. Instead, it prefers to read the files mentioned on the command line first. Only if there is no additional file on the command line, gets falls back to read from STDIN
The question on why you are passing the filename of your ruby program twi times is unfortunately less clear. If you are not calling it that way on your own, this might be caused by some strange environment options in your shell or due to your Ruby setup.
I was curious as well, and found this link How does gets and gets.chomp in ruby work?
Apparently it created a new line therefore could not find the name.
This seemed to work, (following the instructions in the link)
puts "Whats your name?"
name = gets
puts "Hello " + name.chomp + ". How are you?"
Have fun.
Also if you start using rails, you can also test in your console
Example
> def test1
> ...code ..
> end
> test1
#Ray Ban I have used your code
puts "Whats your name?"
name = gets
puts "Hello" + name + ". How are you?"
in gets.rb file and run it using $ ruby gets.rb and it worked as expected.
I am using ruby-2.3.0
Related
I am trying to make a console program that asks the user for their name, and greets them. I am coding in Notepad++, and running it in the git bash console. My code is:
puts "Hello, please type in your name: "
name = gets.chomp
puts "Hello #{name}, it is a pleasure to meet you!"
When it runs, it waits for user input, and once that is entered, it prints:
Hello, please type in your name:
Hello <name_the_user_entered>, it is a pleasure to meet you!
Even though the user prompt is first in the code, it accepts user input before any test is printed. Am I missing something?
Ruby might be buffering output. To force it, use flush:
$stdout.puts "Hello, please type in your name: "
$stdout.flush
name = gets.chomp
puts "Hello #{name}, it is a pleasure to meet you!"
But I think in newer Ruby versions, this shouldn't be necessary.
I was trying the following code:
user = ARGV.first # supposed to ask for user name
puts "Hi, #{user}. How do you like this?"
It does not print as expected. It only prints:
Hi, . Do you like me?
Can someone give me a hint on this?
argv holds the command line arguments.
./your_script.rb USER_NAME
… it has nothing to do with reading data from a prompt.
It looks like you are reading this tutorial. You need to read past the first three lines of code.
The code to read from the prompt is on line 7.
likes = $stdin.gets.chomp
Quentin's given a good answer but he's referring to the "Do you like me?" prompt.
There's no prompt for user name in the Ruby code.
You enter your user name by passing it as an argument to your script.
So, if your script is called "ext14.rb" (as in the tutorial) you would do...
roby ext14.rb Azat
This will put "Azat" in the first element of ARGV (ARGV[0] or ARGV.first) so the user_name variable will contain the string "Azat"
I so decided to make a palindrome program, but I did so by checking a string inputted by a user. In order to do this properly, I wanted to strip away the capitalization, spaces, and punctuation. I managed to get everything but the punctuation part of it working. Every time I try with a string like "Madam, I'm Adam" the program crashes. I am very new to Ruby, and I have only learned my knowledge through the Codecademy website. And I also using the editor provided to run my code. Every time I run it like:
puts "Enter a string!"
user_input = gets.chomp
user_input.downcase!
user_input = user_input.gsub(/[^0-9a-z ]/i, '')
if user_input.include?(" ")
user_input.gsub!(/ /, "")
end
if user_input == user_input.reverse
print "Is a pallindrome"
else
print "Is not a pallindrome"
end
It crashes. But if I run it like:
puts "Enter a string!"
user_input = gets.chomp
user_input.downcase!
if user_input.include?(" ")
user_input.gsub!(/ /, "")
end
if user_input == user_input.reverse
print "Is a pallindrome"
else
print "Is not a pallindrome"
end
It works. What a I doing wrong here? Why does my program always crash when I attempt to take away the punctuation?
Nothing is wrong with your program. Codecademy has a bug reading any input that has a quote in it...
Try it out:
gets
Just enter ' to see it crash...
My advice is to get your own local environment to develop on ruby. There are many many resources out there to help you install a simple ruby environment on any OS.
After that, download and install Sublime Text and start creating your ruby source file. Then you will see that ruby <your_file>.rb will work perfectly as you expect.
I have a task of writing a simple Ruby script which would do the following.
Upon execution from the UNIX command line, it would present the user with a prompt at which he should be able to run certain commands, like "dir", "help" or "exit". Upon "exit" the user should return to the Unix shell.
I'm not asking for the solution; I would just like to know how this "shell" functionality can be implemented in Ruby. How do you present the user with a prompt and interpret commands.
I do not need a CLI script that takes arguments. I need something that creates a shell interface.
The type of program you require can easily be made with just a few simple constructs.
I know you're not asking for a solution, but I'll just give you a skeleton to start off and play around with:
#!/usr/bin/env ruby
def prnthelp
puts "Hello sir, what would you like to do?"
puts "1: dir"
puts "2: exit"
end
def loop
prnthelp
case gets.chomp.to_i
when 1 then puts "you chose dir!"
when 2 then puts "you chose exit!"
exit
end
loop
end
loop
Anyways, this is a simplistic example on how you could do it, but probably the book recommended in the comments is better. But this is just to get you off.
Some commands to get you started are:
somevar = gets
This gets user input. Maybe learn about some string methods to manipulate this input can do you some good. http://ruby-doc.org/core-2.0/String.html
chomp will chop off any whitespace, and to_i converts it to an integer.
Some commands to do Unix stuff:
system('ls -la') #=> outputs the output of that command
exit #=> exits the program
Anyways, if you want this kind of stuff, I think it's not a bad idea to look into http://www.codecademy.com/ basically they teach you Ruby by writing small scripts such as these. However, they maybe not be completely adapted to Unix commands, but user input and the likes are certainly handled.
Edit:
As pointed out do use this at the top of your script:
#!/usr/bin/env ruby
Edit:
Example of chomp vs. chop:
full_name = "My Name is Ravikanth\r\n"
full_name.chop! # => "My Name is Ravikanth"
Now if you run chop and there are no newline characters:
puts full_name #=> "My Name is Ravikanth"
full_name.chop! #=> "My Name is Ravikant"
versus:
puts full_name #=> "My Name is Ravikanth\r\n"
full_name.chomp! #=> "My Name is Ravikanth"
full_name.chomp! #=> "My Name is Ravikanth"
See: "Ruby Chop vs Chomp"
Here's a really basic loop:
#!/user/bin/ruby
#
while true do
print "$ "
$stdout.flush
inputs = gets.strip
puts "got your input: #{inputs}"
# Check for termination, like if they type in 'exit' or whatever...
# Run "system" on inputs like 'dir' or whatever...
end
As Stefan mentioned in a comment, this is a huge topic and there are scenarios that will make this complicated. This is, as I say, a very basic example.
Adding to the two other (valid) answers posted so far be wary of using #!/usr/bin/ruby, because ruby isn't always installed there. You can use this instead:
#!/usr/bin/env ruby
Or if you want warnings:
#!/usr/bin/env ruby -w
That way, your script will work irrespective of differences where ruby might be installed on your server and your laptop.
Edit: also, be sure to look into Thor and Rake.
http://whatisthor.com
http://rake.rubyforge.org
Use irb.
I was looking into an alternative to bash and was thinking along the same lines... but ended up choosing fish: http://fishshell.com/
Nonetheless, I was thinking of using irb and going along the lines of irbtools: https://github.com/janlelis/irbtools
Example:
> irb
Welcome to IRB. You are using ruby 1.9.3p0 (2011-10-30 revision 33570) [x86_64-linux]. Have fun ;)
>> ls #=> ["bin", "share", "opt", "lib", "var", "etc", "src"]
>>
In any case, irb is the ruby shell.
Take a look at cliqr which comes with inbuilt support for build a custom shell https://github.com/anshulverma/cliqr/
Often I find myself doing the following:
print "Input text: "
input = gets.strip
Is there a graceful way to do this in one line? Something like:
puts "Input text: #{input = gets.strip}"
The problem with this is that it waits for the input before displaying the prompt. Any ideas?
I think going with something like what Marc-Andre suggested is going to be the way to go, but why bring in a whole ton of code when you can just define a two line function at the top of whatever script you're going to use:
def prompt(*args)
print(*args)
gets
end
name = prompt "Input name: "
Check out highline:
require "highline/import"
input = ask "Input text: "
One liner hack sure. Graceful...well not exactly.
input = [(print 'Name: '), gets.rstrip][1]
I know this question is old, but I though I'd show what I use as my standard method for getting input.
require 'readline'
def input(prompt="", newline=false)
prompt += "\n" if newline
Readline.readline(prompt, true).squeeze(" ").strip
end
This is really nice because if the user adds weird spaces at the end or in the beginning, it'll remove those, and it keeps a history of what they entered in the past (Change the true to false to not have it do that.). And, if ARGV is not empty, then gets will try to read from a file in ARGV, instead of getting input. Plus, Readline is part of the Ruby standard library so you don't have to install any gems. Also, you can't move your cursor when using gets, but you can with Readline.
And, I know the method isn't one line, but it is when you call it
name = input "What is your name? "
Following #Bryn's lead:
def prompt(default, *args)
print(*args)
result = gets.strip
return result.empty? ? default : result
end
The problem with your proposed solution is that the string to be printed can't be built until the input is read, stripped, and assigned. You could separate each line with a semicolon:
$ ruby -e 'print "Input text: "; input=gets.strip; puts input'
Input text: foo
foo
I found the Inquirer gem by chance and I really like it, I find it way more neat and easy to use than Highline, though it lacks of input validation by its own.
Your example can be written like this
require 'inquirer'
inputs = Ask.input 'Input text'