From: Josselin <josselin@...>
Date: 2007-09-02T15:30:12+09:00
Subject: Re: gsub ?

On 2007-09-01 19:53:01 +0200, Sebastian Hungerecker 
<sepp2k@googlemail.com> said:

> Josselin wrote:
>> I don't manage very well the gsub function, not too bad with simple
>> one, but when it comes to string containing slashes, I totally mess it..
> 
> Use %r{your_regex} instead of /your_regex/ - then you don't have to escape the
> slashes.
> 
>> my string can be srt = "/cities/31550/posts;search"
>> 
>> and I would like
>> 1-   detect that srt is a string of this type      /cities/  nnnnn
>> /posts;search"   where nnnnn is a number between 1 and 99999
> 
> %r{/cities/(\d{1,5})/posts;search}
> \d{1,5} is "one to five digits" and the parens tell it to remember that as
> group 1.
> 
>> 2- if srt is of this type, then replace the number nnnnn by another one
>> ppppp
> 
> srt.sub(%r{/cities/(\d{1,5})/posts;search}) do
>   new_number=$1.to_i * 2 # (Or however the new number is calculated)
>   "/cities/#{new_number}/posts;search"
> end
> If the new number is fixed (i.e. it doesn't depend on the old number), you can
> just do:
> srt[%r{/cities/(\d{1,5})/posts;search},1]="102943"
> 
>> btw : what's the best link to learn more abour gsub... ?
> 
> There's not much to gsub itself. It's just string.gsub(re,str) or
> string.gsub(re) {|match| do_something; return a string}
> What you want to learn more about are regular expressions.
> You can do that at at www.regular-expressions.info
> 
> 
> HTH,
> Sebastian

Thanks a lot you made my SUnday !!