Got help with this code earlier its just checking a file for a line
Im really new to ruby ive used java and C before
just wondering what do i put in if i want to use a variable that is
holding the string eg VAR1 = "hello"
File.foreach "file.txt" do |line|
if /hello/ =~ line
puts "found it"
break
end
end
--
Posted via http://www.ruby-forum.com/.
You can use string interpolation like you can with double quoted strings.
var1 = "hello"
File.foreach "file.txt" do |line|
if /#{var1}/ =~ line
puts "found it"
break
end
end
--Jeremy
On 12/6/07, Peter Loftus <loftuz@gmail.com> wrote:
Got help with this code earlier its just checking a file for a line
Im really new to ruby ive used java and C before
just wondering what do i put in if i want to use a variable that is
holding the string eg VAR1 = "hello"File.foreach "file.txt" do |line|
if /hello/ =~ line
puts "found it"
break
end
end
--
Posted via http://www.ruby-forum.com/\.
--
http://www.jeremymcanally.com/
My books:
Ruby in Practice
My free Ruby e-book
My blogs:
Peter Loftus wrote:
Got help with this code earlier its just checking a file for a line
Im really new to ruby ive used java and C before
just wondering what do i put in if i want to use a variable that is
holding the string eg VAR1 = "hello"File.foreach "file.txt" do |line|
if /hello/ =~ line
puts "found it"
break
end
end
var = "hello"
File.foreach "file.txt" do |line|
if /#{var}/ =~ line
puts "found it"
break
end
end
Perhaps?
Regards,
Lee
--
Posted via http://www.ruby-forum.com/\.
if /#{var1}/ =~ line
when i enter # thats just comments out the whole line
any reason for using #
Jeremy McAnally wrote:
You can use string interpolation like you can with double quoted
strings.var1 = "hello"
File.foreach "file.txt" do |line|
if /#{var1}/ =~ line
puts "found it"
break
end
end
--
Posted via http://www.ruby-forum.com/\.
Sometimes it's better to cache the /#{var}/ as in this case, new
regexp object is created on each pass through the cycle.
That might hurt the performance a bit. So:
var = "hello"
+ var_re = /#{var}/
File.foreach "file.txt" do |line|
- if /#{var}/ =~ line
+ if var_re =~ line
puts "found it"
break
end
end
(This might apply for 1.8 MRI only, other interpreters might be
different): When the regex literal contains #{}, the object
is created on each pass through the code. In the other case it's
created only once.
Jano
On Dec 6, 2007 12:49 PM, Lee Jarvis <ljjarvis@gmail.com> wrote:
Peter Loftus wrote:
if /#{var1}/ =~ line
when i enter # thats just comments out the whole line
any reason for using #
# is not a comment inside a regexp or string
Best regards,
Jari Williamsson
Though your IDE may think you're commenting out the whole line, you're
not. It's the proper way to do string interpolation.
See here: Ruby | zenspider.com | by ryan davis
Or, optionally, the Pickaxe book section on strings.
--Jeremy
On 12/6/07, Peter Loftus <loftuz@gmail.com> wrote:
if /#{var1}/ =~ line
when i enter # thats just comments out the whole line
any reason for using #Jeremy McAnally wrote:
> You can use string interpolation like you can with double quoted
> strings.
>
> var1 = "hello"
>
> File.foreach "file.txt" do |line|
> if /#{var1}/ =~ line
> puts "found it"
> break
> end
> end
>
--
Posted via http://www.ruby-forum.com/\.
--
http://www.jeremymcanally.com/
My books:
Ruby in Practice
My free Ruby e-book
My blogs:
Jano Svitok wrote:
(This might apply for 1.8 MRI only, other interpreters might be
different): When the regex literal contains #{}, the object
is created on each pass through the code. In the other case it's
created only once.
True, you could use the Regexp class also then..
var = 'hello'
revar = Regexp.new(var)
if revar =~ line
#..
end
or perhaps
var = 'hello'
File.foreach 'file.txt' do |line|
if Regexp.new(var) =~ line
puts 'found it'
break
end
end
If you don't care how many times its created and you don't want to use
the '#' in your regexp matches because your IDE doesn't know any better.
Regards,
Lee
--
Posted via http://www.ruby-forum.com/\.
You can also use the /o option, which tells Ruby to compile the Regex
only once:
var = "hello"
File.foreach "file.txt" do |line|
if /#{var}/o =~ line
puts "found it"
break
end
end
On Dec 6, 6:38 am, Jano Svitok <jan.svi...@gmail.com> wrote:
On Dec 6, 2007 12:49 PM, Lee Jarvis <ljjar...@gmail.com> wrote:
Sometimes it's better to cache the /#{var}/ as in this case, new
regexp object is created on each pass through the cycle.
That might hurt the performance a bit. So:> var = "hello"
+ var_re = /#{var}/
> File.foreach "file.txt" do |line|- if /#{var}/ =~ line
+ if var_re =~ line> puts "found it"
> break
> end
> end(This might apply for 1.8 MRI only, other interpreters might be
different): When the regex literal contains #{}, the object
is created on each pass through the code. In the other case it's
created only once.Jano
Thanks for explaining it
Cheers
Loftz
Jeremy McAnally wrote:
Though your IDE may think you're commenting out the whole line, you're
not. It's the proper way to do string interpolation.See here: Ruby | zenspider.com | by ryan davis
Or, optionally, the Pickaxe book section on strings.
--Jeremy
On 12/6/07, Peter Loftus <loftuz@gmail.com> wrote:
>
--
http://www.jeremymcanally.com/My books:
Ruby in Practice
Ruby in PracticeMy free Ruby e-book
http://www.humblelittlerubybook.com/My blogs:
http://www.mrneighborly.com/
http://www.rubyinpractice.com/
--
Posted via http://www.ruby-forum.com/\.
Thanks, I didn't know that... Now I see it even in the first pickaxe
book... I guess I should read it once more 
On Dec 6, 2007 4:35 PM, yermej <yermej@gmail.com> wrote:
You can also use the /o option, which tells Ruby to compile the Regex
only once:var = "hello"
File.foreach "file.txt" do |line|
if /#{var}/o =~ lineputs "found it"
break
end
end
# And don't miss the very useful Regexp.quote, which makes sure
everything in var is matched literally
revar = Regexp.new(Regexp.quote(var))
martin
On Dec 6, 2007 5:17 AM, Lee Jarvis <ljjarvis@gmail.com> wrote:
True, you could use the Regexp class also then..
var = 'hello'
revar = Regexp.new(var)