Learning Ruby

Ruby
1

Hi, I come from a little bit of C programming, an I’ve just started
learning Ruby. So forgive me for the stupid question.
Following the user guide, I found a regular expression example
(rexg.rb), that doesn’t work for me.
If I try to find an exact pattern everything is fine: for example,
searching “foo” in “foobar” returns the correct result. But searching a
regexp pattern doesn’t: “fo+” doesn’t find anything in “foobar”.
I’m running Ruby 1.8 under Linux.
Thank you in advance for your help,

Cristiano

2

Urzahil wrote:

Hi, I come from a little bit of C programming, an I’ve just started
learning Ruby. So forgive me for the stupid question.
Following the user guide, I found a regular expression example
(rexg.rb), that doesn’t work for me.
If I try to find an exact pattern everything is fine: for example,
searching “foo” in “foobar” returns the correct result. But searching a
regexp pattern doesn’t: “fo+” doesn’t find anything in “foobar”.
I’m running Ruby 1.8 under Linux.
Thank you in advance for your help,

Could you provide the examples you have tried? I did not really get you,
as for me:

irb(main):003:0> “foobar” =~ /foo/
=> 0
irb(main):004:0> “foobar” =~ /fo+/
=> 0

your example works. Please send the code snippets which did not work for
you.

Peter
http://www.rubyrailways.com

3

Cristiano M. wrote:

your example works. Please send the code snippets which did not work for
print "str> "
STDOUT.flush
str = gets
break if not str
str.chop!
print "pat> "
STDOUT.flush
re = gets
break if not re
re.chop!
str.gsub! re, “#{st}\&#{en}”

Normal: this code is doing simple string lookup, as in this line, re
is a String and not a Regexp. You should try this instead:

str.gsub!(Regexp.new(re), “#{st}\&#{en}”)

Vince
4

Hi,

On Tue, 2006-10-31 at 20:00 +0900, Peter S. wrote:

Could you provide the examples you have tried? I did not really get you,
as for me:

irb(main):003:0> “foobar” =~ /foo/
=> 0
irb(main):004:0> “foobar” =~ /fo+/
=> 0
your example works. Please send the code snippets which did not work for
you.

I did not explain me too well.
This code works for me too. I was referring to the User Guide example.
Here is the code that doesn’t work for me:

st = “\033[7m”
en = “\033[m”

while TRUE
print "str> "
STDOUT.flush
str = gets
break if not str
str.chop!
print "pat> "
STDOUT.flush
re = gets
break if not re
re.chop!
str.gsub! re, “#{st}\&#{en}”
print str, “\n”
end
print “\n”

Thanks again,
Cristiano

5

On 10/31/06, Cristiano M. [email protected]
wrote:

=> 0
while TRUE
str.gsub! re, “#{st}\&#{en}”
print str, “\n”
end
print “\n”

Thanks again,
Cristiano

Not directly answering your question, but since you are still learning
ruby:

########## LOTSA CODE #########
st = “\033[7m”
en = “\033[m”

$stdout.sync = true

loop do
print "string> "
string = gets.chomp
print "pattern> "
pattern = gets.chomp

puts string.gsub pattern, “#{st}\&#{en}”
end
######## LOTSA CODE END ########

i think that would be a more ‘rubylike’ way to write it… also making
your intention a bit clearer :slight_smile:
you are not in C anymore, you can loosen your grip a little :wink:

^manveru

6

----- Original Message -----
From: “Peter S.” [email protected]
To: “ruby-talk ML” [email protected]
Sent: Tuesday, October 31, 2006 6:00 AM
Subject: Re: Learning R.

the 0 indicates that a match was found at offset 0

“foobar” =~ /oo/
=> 1

“foobar” =~ /boo/
=> nil

In ruby, 0 or empty string is not “false”, only nil or false are false
anything else is true