The Question and Answer Board

[Bob Zumbrunnen]

Do you know Basic? I've always kept a copy of QBASIC.EXE hanging around on my hard drive for anytime I need to write a quick 'n dirty throw-away.

Or, if I'm not mistaken, W2K and later have VBS built in.

Personally, though I'm an old dog none too keen on having to learn yet another set of tricks (when 80% of what I know is obsolete knowledge), I found PERL to be worth the downloading and learning. I use it anytime I need to interact with a website (a few lines of code, and you've got the site's page sitting in memory, ready to run through) or if all I need to do is extract particular lines from a file, which it sounds like you're doing.

For example:

 
 open (INFILE, "filetoprocess.txt"); 
 open (OUTFILE, "resultsfile.txt"); 
 while (<INFILE>) 
 { 
   if (/I like PERL/) 
   { 
     print OUTFILE "$_\n"; 
   } 
 } 
 close INFILE; 
 close OUTFILE; 
 

I think that's about right, but I haven't used it for a bit, so there might be a syntax error or two.

But that quickly reads from one file, and takes every line containing "I like PERL" and writes it (plus a linefeed -- the "\n" thing) to another file.

It's one of the quickest ways to do something like that.

It gets even sweeter, though, if you want to just grab a part of the line in which the text was found. It's got a function called SPLIT that's terribly handy.

But where I like it best is interacting with websites.

For example, SI removes "dead" (threads with no activity for 90 days) threads from its thread search, so a common problem there is trying to find an old thread that hasn't been posted to for a long time. The threads themselves aren't removed. They're just not searchable.

The following bit of code produced the thread list I keep on my sibob site:

 
 require LWP::UserAgent; 
 $ua = new LWP::UserAgent; 
  
 $baseurl="http://www.siliconinvestor.com/stocktalk/subject.gsp\?subjectid\="; 
 $beginthreadnum=1; 
 $endthreadnum=37035; 
 $threadnum=$beginthreadnum; 
  
 open (OUTFILE, ">thread.si"); 
  
 while ($threadnum < $endthreadnum) 
 { 
   $cur_url=$baseurl.$threadnum; 
   print "$threadnum "; 
   $request=new HTTP::Request GET => $cur_url; 
   $response=$ua->request($request, "header.si"); 
   open (MESSAGE, "header.si"); 
   while (<MESSAGE>) 
   { 
     chomp; 
     if (/\<title\>SI\: /) 
     { 
       ($junk, $save)=split(/\<title\>SI\: /, $_); 
       ($threadtitle, $junk)=split(/\<\/title\>/, $save); 
       print OUTFILE "$cur_url / $threadtitle\n"; 
       print "$threadtitle\n"; 
       last; 
     } 
   } 
   close (MESSAGE); 
   $threadnum++; 
   close (OUTFILE); 
   open (OUTFILE, ">>thread.si"); 
 } 
 

It starts with thread 1 and goes up to 37035 (this is really old -- the ending thread number would be considerably higher now), and if a valid page is returned, it looks for whatever is between "<title>SI:" and "</title>", saves that text as the thread name, and also saves the URL, then moves on to the next thread.

I later used QBasic (because I was more comfortable with it for just crunching on strings and reshaping them) to make the HTML, complete with a href's, but I know it can be done in PERL, too. In fact, looking at the PERL code right now, I can see that just one more line is all I'd need to make a ready-to-use HTML.

PERL's a really sweet language for doing a lot of things quickly, especially searching for and dealing with text in files or interacting with a website.