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

i have this code which doeswnt want to work: 
@gb = <GB>; #where GB is a guestbook html file
@gb2 = ("jsdjsjsj");
foreach $line(@bg){
  push(@gb2,$line);
  if($line =~ /INSERT_NEW_ENTRY/){
    push(@gb2,"<b>entry</b> $FORM{'whatever'}");
  }
}
seek(GB,0,0);
truncate(GB,0);
print GB @gb2;

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When I execute this, GB becomes "jsdjsjsj" and not that and whatever was pushed into it. What could I be doing wrong?

Replies are listed 'Best First'.
Re: pushing
by davorg (Chancellor) on Dec 30, 2000 at 18:29 UTC

    Could it be that instead of

    foreach $line (@bg) {

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    you actually meant

    foreach $line (@gb) {

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    Using use strict and -w is a far quicker way of finding these sorts of errors than posting here.

    --
    <http://www.dave.org.uk>

    "Perl makes the fun jobs fun
    and the boring jobs bearable" - me

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      No that was a typing error in the submission and it is @gb in the actual script. It is something else
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        OK. Next guess would be that you're not checking the results of the GB open call (which you haven't shown us) and that therefore your @gb array ends up empty.

        What gets written to the error log? Have you tried running the script from the command line?

        --
        <http://www.dave.org.uk>

        "Perl makes the fun jobs fun
        and the boring jobs bearable" - me

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Re: pushing
by lhoward (Vicar) on Dec 30, 2000 at 18:36 UTC
    always "use strict" and enable warning. That would have found this problem immediately. You named one of your variables incorrectly. Your code should read (the change is in bold): 
    
  @gb = <GB>; #where GB is a guestbook html file
  @gb2 = ("jsdjsjsj");
  foreach $line(@gb){
    push(@gb2,$line);
    if($line =~ /INSERT_NEW_ENTRY/){
      push(@gb2,"<b>entry</b> $FORM{'whatever'}");
    }
  }
  seek(GB,0,0);
  truncate(GB,0);
  print GB @gb2;
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      use strict -w; doesnt do anything!!
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        I think you'll find they do if you read your error log!

        Try adding

        use CGI::Carp qw(fatalsToBrowser);

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        to the script.

        --
        <http://www.dave.org.uk>

        "Perl makes the fun jobs fun
        and the boring jobs bearable" - me

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        This problem is a great example of why use strict is such a lifesaver. But perhaps lhoward was overly subtle. He provided a corrected code fragment without calling attention to the correction.

        Read his code again, carefully. If necessary, copy/paste it into a file and diff it against your source.

        If you're already doing use strict and aren't getting any error messages, then there's a different type of programming lesson waiting for you as when you compare the code snippets.

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Re: pushing
by jeroenes (Priest) on Dec 30, 2000 at 18:48 UTC
    You have to reopen your filehandle for writing. So before the seek, you should have something like: 
    close GB;
open( GB, ">$file");

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    You than can even leave the seek and truncate out.

    Hope this helps,

    Jeroen
    I was dreaming of guitarnotes that would irritate an executive kind of guy (FZ)

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