From: Robert Klemme <shortcutter@...>
Date: 2011-08-31T22:50:52+09:00
Subject: Re: Prepend a character to a string in ruby

On Wed, Aug 31, 2011 at 1:00 PM, ruby rails <rubyonrails4me@gmail.com> wrote:
> I am trying to insert a character to a string at the beginning of a
> string. How is it possible in ruby.
> I tried using
>    s.times do |s|
>    @space_availability+="0"
>      end
> But this would add at the end of the string.
> The @space_availability is a string with 1's and 0's. I need to add 0's
> at the beginning of this string.
> I am a newbie in ruby

You can use String#rjust

irb(main):023:0> @space_availability = 'x'
=> "x"
irb(main):024:0> @space_availability = @space_availability.rjust 5, '0'
=> "0000x"

However, chances are that you want printf, sprintf or % operator.  For example

irb(main):013:0> sprintf '%0*d', 10, 8
=> "0000000008"

So, for numbers

@space_availability = sprintf '%0*d', s, int_value

If you want the string to represent a binary number you can do

irb(main):015:0> sprintf '%0*b', 8, 123
=> "01111011"

Note, the '*' in the format string indicates there is an argument
indicating the length before the value.  If the length is fixed you
can replace '*' with the length:

irb(main):016:0> sprintf '%08b', 8, 123
=> "00001000"

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/