Thanks for your help and for the detailed info :) (Needless to say it works fine when i changed it to while (<>) )
"Sudarshan Raghavan" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Babylon wrote: > > >I know how it's supposed to be done but when i tried it in a program i'm > >writing at the moment it isn't working quite how i expected. > > > >The program is, in it's simplest form (which still doesn't work): > >------------------------------------------------------ > >#!perl > > > >for $file (<s2/*>) > >{ > > push @ARGV, $file; > >} > > > > Read through this document to find out how the null filehandle (<>) works > perldoc perlop #Search for 'null filehandle' > This will give you info on the -i switch ($^I is a mnemonic for the -i > switch) > perldoc perlrun > > > > >$^I = "~"; > >for (<>) > > > > Short answer: > change the above line to while (<>) and things will work fine. > > Long answer: > The -i switch or the value of $^I apply only when the <> construct is > currently processing. The for (<>) is equivalent to slurping in the > contents of all the files present in the @ARGV array (perldoc perlsyn). > The for construct creates a flat list before actually executing the loop > body. <> processing has already finished when the loop body is being > executed. > > Why is the original file empty? > When the <> construct is processing and the $^I has been set, the > filehandle to the currently open file is selected (perldoc -f select, > one argument form of select). All print statements without a filehandle > argument will be directed at this filehandle (perldoc -f print). As a > result of no print statements being made when <> was processing, the > original file ends up being empty. > > Why does the output appear on the standard output? > This is the result of modifying and printing the contents of the list > created by the for construct. Note: The default selected filehandle is > STDOUT. > > The while loop on the other hand steps through the contents one line at > a time (the default behaviour). This means that the loop body is being > executed when the <> construct is still processing. > > > > > >{ > > > > s/(<td .*?>)/<td>/g; > > print; > >} > >------------------------------------------------------ > > > >The problem is that the print statement sends everything to the command > >console output, not the file i'm try to edit in-place. The original file > >name ends up being completely blank after running the script, but at least > >the backup is created. > > > >I'm using perl 5.8, and WindowsXP. > > > > > >Also, yes, that is a search for html tags but it's to do some massive batch > >conversion on a website i made a few years back so i know what i'm working > >with and that it will work all work correctly. > > > >The script isn't really the full story... It's just what i'm doing in the > >most basic form, that still doesn't work ;) > > > >So, can anyone work out what's wrong? Have i done something wrong in my > >script? > > > > > > > > > > > -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
