Regexp.match(line) question

[m b]

Hi=2C
I new to Ruby. It's a lot of fun to learn..

if I do this:

f=3Dopen('filename.dat'=2C'r')
str=3Df.read

and then:

str.each_line do |line|
/ruby/.match(line)

ruby prints out variable line and say its a RegexpError
'empty range in character class' as if it interprets line as a Regexp
What am I doing wrong? There are a lot of strange characters in variable l=
ine=2C
maybe that is the issue?
=

 

[Jesús Gabriel y Galán]

Hi,
I new to Ruby. =A0It's a lot of fun to learn..

if I do this:

f=3Dopen('filename.dat','r')
str=3Df.read

and then:

str.each_line =A0do |line|
=A0 =A0/ruby/.match(line)

ruby prints out variable line and say its a RegexpError
'empty range in character class' =A0as if it interprets =A0line as a Rege= xp
What am I doing wrong? =A0There are a lot of strange characters in variab= le line,
maybe that is the issue?

I'm not sure about the issue, but the usual idiom for this is:

File.foreach("filename.dat") do |line|
line.match(/ruby/)
end

This way:
- The file handler is automatically closed for you, you don't have to
ensure that you call close on it, it's done for you.
- You only have one line at a time in memory, since that seems to be
your unit of data. If the file is huge it will make a difference in
the amount of memory you will consume at a time.

In any case, String#match calls Regexp#match, so calling match on one
or the other should make no difference. Can you show a small example
of a file that breaks?

Jesus.

 

[m b]

=20
I'm not sure about the issue=2C but the usual idiom for this is:
=20
File.foreach("filename.dat") do |line|
line.match(/ruby/)
end
=20
This way:
- The file handler is automatically closed for you=2C you don't have to
ensure that you call close on it=2C it's done for you.
- You only have one line at a time in memory=2C since that seems to be
your unit of data. If the file is huge it will make a difference in
the amount of memory you will consume at a time.
=20
In any case=2C String#match calls Regexp#match=2C so calling match on one
or the other should make no difference. Can you show a small example
of a file that breaks?
=20
Jesus.

Aha.. Thats a better way to do it.. File.foreach Thanx.



the string-variable line both starts and and ends with a '/' . Its =
a series of paths from a linux system hd =20

But its a String to be searched and not a Regexp




=

 

[m b]

I found out what I was doing the wrong way..

I'm reading the search pattern with readline
and I wrote it -->/ruby/ =20
That didnt make it a Regexp.
Now I found that if I write it -->ruby
and then
pattern=3DRegexp.new(input_str) it works..

/Mix


=

 

[Robert Klemme]

You must have a different regular expression in your test other than
/ruby/ because that is valid:

irb(main):001:0> m =3D /ruby/.match "text"
=3D> nil
irb(main):002:0> m =3D /ruby/.match "ruby"

I found out what I was doing the wrong way..

I'm reading the search pattern with =A0readline
and I wrote it -->/ruby/
That didnt make it a Regexp.

This is not true. The sequence /ruby/ *is* a valid regular expression.

10:01:30 ~$ ruby19 -e 'p /ruby/'
/ruby/
10:01:38 ~$ ruby19 -e 'p /ruby/.class'
Regexp
10:01:42 ~$

There must be something else going on. Please post your _complete_
code you actually have.

Kind regards

robert


--=20
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/