Replacing numbers with links

danambroseUK has asked for the wisdom of the Perl Monks concerning the following question:

Hello,

I have unstructured strings which contain ID reference numbers inline. A reference number is made up of between 3-5 digits i.e 200, 50210, 121, 3222 etc.

What I would like to do is change all of the numbers into hyperlinks; to the URL lookup.cgi?id=XXXXX.

I tried doing a match to extract the numbers, then a substitution to replace - this works fine, except that as the URL also contains a number of 3-5digits in length, this screws the substitution.

sub Linker {
    
    ($mystring)=@_;
        
    @myarray = ($mystring =~ m/(\d\d\d+)/g);

    foreach $a (@myarray){
    
        $url = "<b><a href='lookup.cgi?id=$a'>$a</a></b>";
    
        $mystring=~s/$a/$url/g;
            
    }
    
    return $mystring;
    
}
[download]

Any ideas? Maybe a solution that does the match, and substitution in one go?
Thanks in advance
Dan

Comment on Replacing numbers with links Download Code

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Re: Replacing numbers with links by liverpole (Monsignor) on Jul 16, 2006 at 14:28 UTC
Hi danambroseUK, What I think you want to do is replace all of the number strings in a single, global regular expression substitute. You could do this with, for example: `$mystring =~ s/(\d{3,5})/<b><a href='lookup.cgi?id=$1<\/a>/g;` [download] Several things to note: 1) you can change the \d{3,5} if it turns out you have numeric strings which are less than 3 or greater than 5 digits. 2) you need to escape the '/' in <\/a>, since it would improperly terminate the regex otherwise. 3) the expression $1 is a backreference, used to specify the thing that was matched. s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/	[reply] [d/l]
Re^2: Replacing numbers with links by johngg (Canon) on Jul 16, 2006 at 15:36 UTC
you need to escape the '/' in <\/a>, since it would improperly terminate the regex otherwise. or use something other than a forward slash as your regex delimiter, for example paired curly brackets like this `$mystring =~ s{(\d{3,5})} {<b><a href='lookup.cgi?id=$1</a>}g;` [download] You often see matching against *nix paths using the default forward slash delimiter (and omitting the `m` as it is not required with `/ ... /`) when using a different delimiter would be more readable. `if( $path =~ /\/path\/to\/file/ ) { ... }` [download] is, I feel, much harder to read than `if( $path =~ m{/path/to/file} ) { ... }` [download] Cheers, JohnGG	[reply] [d/l] [select]
Re^2: Replacing numbers with links by GrandFather (Saint) on Jul 16, 2006 at 17:59 UTC
As it stands the regex will match a minimum of 3 and maximum of 5 digits, but doesn't care if they are part of a large number of digits or are imbedded in text. `use strict; use warnings; while (<DATA>) { s\|\b(\d{3,5})\b\|<b><a href='lookup.cgi?id=$1</a></b>\|g; print; } __DATA__ foo 300 bar bas. foo300bar bas. foo 123456 bar 1234 bas 56789. foo bar bas. 1 foo 1 bar 2 bas bas.` [download] Prints: `foo <b><a href='lookup.cgi?id=300</a></b> bar bas. foo300bar bas. foo 123456 bar <b><a href='lookup.cgi?id=1234</a></b> bas <b><a href=' +lookup.cgi?id=56789</a></b>. foo bar bas. 1 foo 1 bar 2 bas bas.` [download] ~~Is it a concern that the substitution introduces an orphaned bold tag for each substitution made?~~ Update: fixed bold tags and changed regex delimiters to avoid picket fence DWIM is Perl's answer to Gödel	[reply] [d/l] [select]
Re^2: Replacing numbers with links by Anonymous Monk on Jul 16, 2006 at 18:03 UTC
Liverpole... A perfect solution to my problem within 10minutes! It works a treat - Thats going to save me all morning tomorrow scratching my head! Much appricaite your help :) Dan	[reply]