Perl: Carriage Return???

Andrew DeFaria
Sat Apr 28 14:40:00 GMT 2007

Alexander Konig wrote:
> Hello
> I am reading OÂŽReilllyÂŽs "Learning Perl" Book and doing the exercises. 
> My version of a test script for regular expression was :
> ?
> while( <INPUT> ){
> chomp;
> if( /$pattern/ ){
> print "\nHit: |$`>$&<$'|";
> }
> else{
> if( !$option ){
> print "\n\nNo Hit >$pattern< in >$_< !";
> }
> }
> }
> ?
> The output for this code is :
> < !Hit >fred< in >Frederic
> < !Hit >fred< in >Mr.Smith
> |it: |Nar>fred<
> I cannot imagine what is going wrong with that. Why some parts are 
> just overwritten.
> The same code using Active Perl works. Some weeks ago this script has 
> worked using Cygwin, too.
> Then, I wanted to check a regular expression with this script I had to 
> see this weird output.
> Could please someone help me. I really love working with Cygwin when 
> using Windows.
Learn to use the Perl debugger. It's invaluable and teaches you how Perl 
works internally as you learn it more. Here's a cheat sheet:

Given the above I would do perl -d <your script> then I would have 
(c)ontinued to the first if statement and used x $_ to dump out the 
contents that variable and probably would have noticed the extra line 
feed in that variable. That would have led me to the realization that 
DOS style files have both CRs and LFs and that Cygwin's Perl, being more 
Unix like than DOS like, only deals with LFs. One solution to this is to:

    chop if /\r/;

Which will chomp the CR (\n) and chop off the LF (\r) if there is one.
Andrew DeFaria <>
Making music should not be left to the professionals. - Michelle Shocked

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