can i do something like this?
string = "123" + rand(10).to_s + "abc"
=> "1237abc"
string.include?("123" + string.any_character(1) + "abc") # any_character(digit)
=> true
the point is to know a part of a string like lets say a html tag string, testing for something like Name Changes Every Day
and easily find the title from the source every time no matter what it might be, but for me, it will always be one character, soooooo, any help here?
Try that code:
string = "123" + rand(10).to_s + "abc"
string =~ /123\dabc/
0 means that pattern starts at 0 character. This return nil when pattern doesnt match. If you want to match only whole text change /123\dabc/ into /^123\dabc$/
You can just use regular expressions with ruby. Example:
string = "123" + rand(10).to_s + "abc"
string.match /123\dabc/
Related
I am newbie in ruby. In my ruby program, there is a part of code for parsing geocode. The code is like below:
string = "GPS:3;S23.164865;E113.428970;88"
info = string.tr("GPS:",'')
info_array = info.split(";")
puts "GPS: #{info_array[0]},#{info_array[1]},#{info_array[2]}"
The code should split the string into 3 piece: 3, S23.164865 and E113.428970;88 and the expected output is
GPS: 3,S23.164865,E113.428970
but the result is:
GPS: 3,23.164865,E113.428970
Yes, the 'S' letter disappered...
If I use
string = "GPS:3;N23.164865;E113.428970;88"
info = string.tr("GPS:",'')
info_array = info.split(";")
puts "GPS: #{info_array[0]},#{info_array[1]},#{info_array[2]}"
, it prints expected result
GPS: 3,N23.164865,E113.428970
I am very confused why this happens. Can you help?
It looks like you were expecting String#tr to behave like String#gsub.
Calling string.tr("GPS:", '') does not replace the complete string "GPS:" with the empty string. Instead, it replaces any character from within the string "GPS:" with an empty string. Commonly you will find .tr() called with an equal number of input and replacement characters, and in that case the input character is replaced by the output character in the corresponding position. But the way you have called it with only the empty string '' as its translation argument, will delete any of G, P, S, : from anywhere within the string.
>> "String with S and G and a: P".tr("GPS:", '')
=> "tring with and and a "
Instead, use .gsub('GPS:', '') to replace the complete match as a group.
string = "GPS:3;S23.164865;E113.428970;88"
info = string.gsub('GPS:', '')
info_array = info.split(";")
puts "GPS: #{info_array[0]},#{info_array[1]},#{info_array[2]}"
# prints
GPS: 3,S23.164865,E113.428970
Here we've called .gsub() with a string argument. It is probably more often called with a regexp search match argument though.
I've had a look round and can't find what I need on Stack Overflow, and was wondering if someone had a simple solution.
I want to find a parameter within a URL and increment its value, so, as an example:
?kws=&pstc=&cty=&prvnm=1
I want to be able to locate the prvnm parameter no matter where it is in the string and increment its value by 1.
I know I could split the parameters into an array, find the key, increment it and write it back but that seems rather long winded and wondered if someone else had any ideas!
require "uri"
url = "http://example.com/?kws=&pstc=&cty=&prvnm=1"
def new_url(url)
uri = URI.parse(url)
hsh = Hash[URI.decode_www_form(uri.query)]
hsh['prvnm'] = hsh['prvnm'].next
uri.query = URI.encode_www_form(hsh).to_s
uri.to_s
end
new_url(url) # => "http://example.com/?kws=&pstc=&cty=&prvnm=2"
There are already four answers, so I had to come up with something a little different:
s = "?kws=&pstc=&cty=&prvnm=1"
head, sep, tail = s.partition(/(?<=[?&]prvnm=)\d+/)
head + (sep.to_i + 1).to_s + tail # => "?kws=&pstc=&cty=&prvnm=2"
'String#partition' returns an array of three strings [head, sep, tail], such that head + sep + tail => s, where separator is partition's argument, which can be a string or a regex.
We want the separator to be the digits following &prvnm=. We therefore use a regex with \d+ preceeded by the aforementioned string which we want to treat as having zero length, so it will not be included in the separator. That calls for a "positive look-behind": (?<=&prvnm=). \d+ is "greedy", so it take all consequetive digits.
For the given value of s, head, sep, tail = s.partition(/(?<=&prvnm=)(\d+)/)
=> ["?kws=&pstc=&cty=&prvnm=", "1", ""].
Edit: my thanks to #quetzalcoatl for pointing out that I needed to change (?<=&prvnm=) in my regex to what I have now, as what I had would fail when ?prvnm= was at the beginning of the string.
split the string by `&`
then iterate over the parts
then split each part by `=` and inspect the results
when found `prvnm`, parse the integer and increment it
then join the bits by '='
then join the parts by '&'
Or, use regex like:
/[?&]prvnm=\d+/
and parse the result and then do a replacement.
Or, get some URL-parsing library..
Try something like this:
params = "?kws=&pstc=&cty=&prvnm=1"
num = params.scan(/prvnm=(\d)/)[0].join.to_i
puts num + 1
Use:
require 'uri'
Then:
parsed-url= URI.parse( ur full url)
r = CGI.parse(parsed_url.query)
r is now a hash of all your query parameters.
You can easily access it by using:
r["prsvn"].to_i + 1
Hello I am trying to build a simple action in Ruby that takes one string like
result = "This is my javascript variable 'var first = 1 + 1;' and here is another 'var second = 2 + 2;' and that's it!"
So basically I would like to take the text within single quotes ' or backticks ` and and replace it by:
<code>original text</code> note I'm replacing it by an opening and closing code tag
Just like in markdown
so I would have a result like
result = "This is my javascript variable <code>var first = 1 + 1;<code> and here is another <code>var second = 2 + 2;</code> and that's it"
If it's possible to run this natively without the need of any extra gem it would be great :)
Thanks a lot
I guess you'll need to iterate the string and parse it. While you can do non-greedy regex matches, e.g. result.gsub!(/'([^']*)'/, '<code>\1</code>') you might find the result might not behave correctly in corner-cases.
Without any other advanced requirement
>> result.gsub(/\s+'/,"<code>").gsub(/'\s+/,"</code>")
=> "This is my javascript variable<code>var first = 1 + 1;</code>and here is another<code>var second = 2 + 2;</code>and that's it!"
You will need to come-up with a character as a delimiter for your code, which you don't use otherwise..
Why? because of all the corner cases. E.g. the following string
result = "This's my javascript variable 'var first = 1 + 1;' and here is another 'var second = 2 + 2;' and that's it!"
which would otherwise produce:
"This<code>s my javascript variable </code>var first = 1 + 1;<code> and here is another </code>var second = 2 + 2;<code> and that</code>s it!"
Total garbage out..
However if you use a unique character as a delimiter that's otherwise not used, you can create a non-greedy RegExp which will do the search/replace
e.g. using a # character to delimit the code:
"This's my javascript variable #var first = 1 + 1;# and here is another #var second = 2 + 2;# and that's it!"
I have a string in Ruby:
str = "<TAG1>Text 1<TAG1>Text 2"
I want to use gsub to get a string like this:
want = "<TAG2>Text 1</TAG2><TAG2>Text2</TAG2>"
In other words, I want to save everything in between a <TAG1> and EITHER: 1) the next occurrence of a "<", or 2) the end of the string.
The best regex i could come up with was:
regex = /<TAG1>(.*)(?:<|$)/
But the problem with this is that it'll just match the entire str, where what I want is both matches within str. (In other words, it seems like the end of string char ($) seems to have precedence over the "<" character--is there a way to flip it around?
/<TAG1>([^<]*)/ will match that. If there's no < it'll go all the way to the end of the string. Otherwise it will stop when it hits a <. Your problem is that . matches < as well. An alternative way would be to do /<TAG1>(.*?)(?:<|$)/, which makes the * non-greedy.
I want to extract the quoted substrings from inside a string. This is an example:
string = 'aaaa' + string_var_x + 'bbbb' + string_var_y
The output after parsing should be:
["'aaaa'", "'bbbb'"]
The initial solution was to string.scan /'\w'/ which is almost ok.
Still I can't get it working on more complex string, as it's implied that inside '...' there can be any kind of characters (including numbers, and !##$%^&*() whatever).
Any ideas?
I wonder if there's some way to make /'.*'/ working, but make it less greedy?
Lazy should fix this:
/'.*?'/
Another possibility is to use this:
/'[^']*'/
An alternate way to do it is:
>> %{string = 'aaaa' + string_var_x + 'bbbb' + string_var_y}.scan(/'[^'].+?'/)
#=> ["'aaaa'", "'bbbb'"]
String.scan gets overlooked a lot.