From: Glen Pfeiffer <glen@...>
Date: 2007-01-23T12:05:12+09:00
Subject: Re: Problems with replacing text

--- Sam C. wrote:
> I am creating a small chatbot program in Ruby, and I need it
> to be able to change the word "I" to "You" when it is reading
> the user input. this is the code I am using:
> 
> uinput['I'] = 'you'

You want to perform a "substitution" on the text contained in the
variable. You can call the 'gsub!' method of the string object to
perform a substitution. Here is an example from an irb session:

	irb(main):001:0> x = 'I love Perl'
	=> "I love Perl"
	irb(main):002:0> x.gsub!('Perl', 'Ruby')
	=> "I love Ruby"
	irb(main):003:0> puts x
	I love Perl

The code only version is:

	x = 'I love Perl'
	x.gsub!('Perl', 'Ruby')
	puts x

There are several other problems you may run into with this as 
well. For example, what are you going to do when the user enters 
a lowercase i? Or what if a word contains the letter i? I 
recommend using a regular expression.

Regular Expressions:
http://www.rubycentral.com/book/tut_stdtypes.html#S4

Pattern-Based Substitution
http://www.rubycentral.com/book/tut_stdtypes.html#UK

Here is another irb session:

	irb(main):004:0> x = 'I will eat pizza for dinner!'
	=> "I will eat pizza for dinner!"
	irb(main):005:0> x.gsub!(/\bi\b/i, 'You')
	=> "You will eat pizza for dinner!"
	irb(main):006:0> puts x
	You will eat pizza for dinner!
	=> nil

Again, the code only version:

	x = 'I will eat pizza for dinner!'
	x.gsub!(/\bi\b/i, 'You')
	puts x

--
Glen