I'm trying to test that a regex will match a 2-digit number. I get:
11 =~ /^\d{1,2}$/
# => nil
Yet the regex works flawlessly on Rubular. What am I doing wrong?
The problem is that you are testing the regex against a number and not a string. Regexes are intended for matching strings. Simply:
'11' =~ /^\d{1,2}$/
or
11.to_s =~ /^\d{1,2}$/
You are calling Kernel#=~, which always returns nil.
Rubular does not interpret your input as Ruby code, it interprets is as string literal. That is why it works there.
You are applying regex on number instead of string so convert it to string and try again.
Related
I am a newbie in Ruby, I'm using version 1.9.3. I have the following regular expression:
/\\\//
As far as I know, it should match a string which has the characters '\' and '/', one following the other, right?
I am using the following code in order to get true in case the regex matches the string or symbol in the far right:
!(regex !~ :"string or symbol to match")
Because using =~ gives me the index of the match and I simply want a boolean. Besides, I'm trying to see how ugly or hackish can Ruby look compared to C :P
When I try to match the symbol :\/ the IRB prompt changes to an asterisk, and returns nothing. Why?
When I try to match the string "\/" my little ugly snippet returns false. Why?
The symbol :\/ is not a valid symbol. You could do :'\/' if you wanted a symbol version of the string '\/'. And when you feed it "\/" it is false because that has double quotes so it is actually the string '/' so you actually want either '\/' or "\\/".
Finally, it's better code and convention to do your test like so:
!!(regex =~ :'\/')
!!(regex =~ '\/')
!!(regex =~ "\\/")
I'm trying the same super simple regex on Rubular.com and my VM Linux with Ruby 1.9.2 I dont' know why I'm getting different outputs:
VM:
my_str = "Madam Anita"
puts my_str[/\w/]
this Outputs: Madam
on Rubular it outputs: MadamAnita
Rubular:
http://www.rubular.com/r/qyQipItdes
I would love some help. I stuck here. I will not be able to test my code for the hw1.
No, it doesn't really. It matches all characters in "Madam" and "Anita", but not the space. The problem you are having is that my_str[/\w/] only returns a single match for the given regular expression, whereas Rubular highlights all possible matches.
If you need all occurrences, you could do this:
1.9.3p194 :002 > "Madam Anita".scan(/\w+/)
=> ["Madam", "", "Anita", ""]
Actually, \w matches a single character. The result in Rubular contains spaces between adjacent characters to tell you this (though I wish they'd also make the highlighting more obvious...). Compare with the output from matching \w+, which matches two strings (Madam and Anita).
I want to make a case sensitive comparision like this:
If ARGV[0].eql? /word/i
print "yep! ^^"
elsif
print "nope :("
end
But that don't works... Don't recognizes "word"
I've tryed too quoteing and escaping chars...
What i'm doing wrong?
Thankyou
Probably you should use =~ operator, then
"word" =~ /word/i
works fine
http://www.regular-expressions.info/ruby.html
The problem is that you are trying to compare a regex to a string. By changing /word/i to 'word' it should work.
I want to split the following strings into two substrings.
"somestring(otherstring)"
I came with the following regex split
"somestring(otherstring)".split(/(.+)\((.+)\)/)
but this excludes the following strings, which dont have the substring in braces..
"somestring"
how can change the regex so that, even if there is not substring of the pattern "(otherstring)", it still generates the first substring as output.
thanks a lot in advance!
>> "somestring(otherstring)".split(/[()]/)
=> ["somestring", "otherstring"]
>> "somestring".split(/[()]/)
=> ["somestring"]
Try using something like this as the regex: /([^\(\)]+)(?:\((.+)\))?/.
I'm trying to learn RegEx in Ruby, based on what I'm reading in "The Rails Way". But, even this simple example has me stumped. I can't tell if it is a typo or not:
text.gsub(/\s/, "-").gsub([^\W-], '').downcase
It seems to me that this would replace all spaces with -, then anywhere a string starts with a non letter or number followed by a dash, replace that with ''. But, using irb, it fails first on ^:
syntax error, unexpected '^', expecting ']'
If I take out the ^, it fails again on the W.
>> text = "I love spaces"
=> "I love spaces"
>> text.gsub(/\s/, "-").gsub(/[^\W-]/, '').downcase
=> "--"
Missing //
Although this makes a little more sense :-)
>> text.gsub(/\s/, "-").gsub(/([^\W-])/, '\1').downcase
=> "i-love-spaces"
And this is probably what is meant
>> text.gsub(/\s/, "-").gsub(/[^\w-]/, '').downcase
=> "i-love-spaces"
\W means "not a word"
\w means "a word"
The // generate a regexp object
/[^\W-]/.class
=> Regexp
Step 1: Add this to your bookmarks. Whenever I need to look up regexes, it's my first stop
Step 2: Let's walk through your code
text.gsub(/\s/, "-")
You're calling the gsub function, and giving it 2 parameters.
The first parameter is /\s/, which is ruby for "create a new regexp containing \s (the // are like special "" for regexes).
The second parameter is the string "-".
This will therefore replace all whitespace characters with hyphens. So far, so good.
.gsub([^\W-], '').downcase
Next you call gsub again, passing it 2 parameters.
The first parameter is [^\W-]. Because we didn't quote it in forward-slashes, ruby will literally try run that code. [] creates an array, then it tries to put ^\W- into the array, which is not valid code, so it breaks.
Changing it to /[^\W-]/ gives us a valid regex.
Looking at the regex, the [] says 'match any character in this group. The group contains \W (which means non-word character) and -, so the regex should match any non-word character, or any hyphen.
As the second thing you pass to gsub is an empty string, it should end up replacing all the non-word characters and hyphens with empty string (thereby stripping them out )
.downcase
Which just converts the string to lower case.
Hope this helps :-)
You forgot the slashes. It should be /[^\W-]/
Well, .gsub(/[^\W-]/,'') says replace anything that's a not word nor a - for nothing.
You probably want
>> text.gsub(/\s/, "-").gsub(/[^\w-]/, '').downcase
=> "i-love-spaces"
Lower case \w (\W is just the opposite)
The slashes are to say that the thing between them is a regular expression, much like quotes say the thing between them is a string.