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

I'm very PERL illiterate, so please help.

I have a file that read in strings such as 

AlarmForwarderServer.exe,app_common.dll,DsCommon.dll,DSGccCommon.dll,D
+sRffCommon.dll,DsGccProxy.dll,DsRffProxy.dll,

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this is the format per line, the exe followed by a list of dlls. I want to search for the .exe and pust it on @myarray with a [<exe name.}, then I want to keep parsing the string and put the dll under it.

I keep getting compile errors. Here is the code I have. 

foreach $line (@exeDllLines) # loop thru list 
{   
    chomp($line);  # chop off trailing newlines 
    #find exe
    print "$line";
    
    if( $line =~ m/exe/ )
    {
       $line = "[$line]";
        push @dllarray, $line;
    }
            
    if( $line =~ m/dll/ )
    {
        push @dllarray, $line;           
    }

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I know there is probably a one liner out there, but PERL is so new, I'm still coding as if in C++.

Thanks for the help

Edit: g0n Code tags round example data

Replies are listed 'Best First'.
Re: noob regexpression question
by polettix (Vicar) on Nov 07, 2005 at 16:42 UTC
    I keep getting compile errors.
    Try to put the following at the beginning of your script:
    use strict;
use warnings;
use diagnostics;

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    and you should get better info about what's going wrong. At a first glance, you're missing the foreach closing brace. Please note that using strict obliges you to declare all your variables before you use them, which you should appreciate as a C++ programmer :)

    If each $line contains the whole stuff, you'll have hard times. You should probably split using "," as a separator, then iterate thru the elements:

    foreach my $line (@lines) {
   chomp $line;
   foreach my $element (split /,/ , $line) {
      my $extension = substr($element, -3) || '';
      if ( $extension eq 'exe' ) {
          push @dllarray, "[$element]";
      }           
      elsif ( $extension eq 'dll' )
      {
          push @dllarray, $element;           
      }      
   }
}

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    Note: CODE UNTESTED!!!

    Flavio
    perl -ple'$_=reverse' <<<ti.xittelop@oivalf

    Don't fool yourself.
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      The || '' doesn't help, and you'll fail for "foodll". 
            ...
      my $extension = substr($element, -3) || '';
      if ( $extension eq 'exe' ) {
      ...
      elsif ( $extension eq 'dll' )
      ...

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      should be 
            ...
      my $extension = substr($element, -4);
      if ( $extension eq '.exe' ) {
      ...
      elsif ( $extension eq '.dll' )
      ...

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        D'ho, lucky me that I put the big "untested code" :) I was convinced that the substr function would return undef if the string was empty (like the middle element in "ciccio.exe,,pallo.dll"), but it is simply the empty string.

        I could agree on the second correction, but only on a robustness ground that seems not necessary in this case. Anyway, better being overprotective, especially when it's cheap and helps building the right attitude.

        Flavio
        perl -ple'$_=reverse' <<<ti.xittelop@oivalf

        Don't fool yourself.
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Re: noob regexpression question
by sgifford (Prior) on Nov 07, 2005 at 16:40 UTC
    The code you have is missing the final, closing curly brace. If I add that in, this compiles fine.
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Re: noob regexpression question
by jdporter (Paladin) on Nov 07, 2005 at 17:45 UTC

    Your code pushes the entire line onto the array for each match. Is that really what you want? Because that means a line such as the sample you gave causes two elements to be pushed onto the array: 

    [AlarmForwarderServer.exe,app_common.dll,DsCommon.dll,DSGccCommon.dll,
+DsRffCommon.dll,DsGccProxy.dll,DsRffProxy.dll,]
AlarmForwarderServer.exe,app_common.dll,DsCommon.dll,DSGccCommon.dll,D
+sRffCommon.dll,DsGccProxy.dll,DsRffProxy.dll,

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    If your goal is to have a list of dlls associated with each exe, then you should split each line on commas first. The resulting list of strings you can push onto an array: 

    my @dllarray = map {
        chomp;
        [ split /,/ ]
} @exeDllLines;

# iterate over the collected data:

for ( @dllarray )
{
    my( $exe, @dlls ) = @$_;
    print "$exe uses the following DLLs:\n";
    print "$\t$_\n" for @dlls;
}

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    However, a more robust solution would use a hash: 

    my %exeDll;
for ( @exeDllLines )
{
        chomp;
        my @a = grep /\S/, split /,/; # split on comma; filter out emp
+ty fields
        my @dlls = grep /\.dll$/, @a; # get list of dll files
        for my $exe ( grep /\.exe$/, @a )
        {
                @{$exeDll{$exe}}{@dlls} = ()
                # OR:
                $exeDll{$exe}{$_}++ for @dlls;
        }
}

# then you can iterate over the collected data:

for my $exe ( sort keys %exeDll )
{
    print "$exe uses the following DLLs:\n";
    for my $dll ( sort keys %{ $exeDll{$exe} } )
    {
        print "\t$dll\n";
    }
}

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    We're building the house of the future together.
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Re: noob regexpression question
by ikegami (Patriarch) on Nov 07, 2005 at 16:41 UTC

    Although not a *compile* error, you should replace m/exe/ and m/dll/ with m/\.exe$/i and m/\.dll$/i.

    By the way, the following is equivalent (minus the prints) to your code:

    chomp(@exeDllLines);
my @dllarray = grep { /\.(?:dll|exe)$/i } @exeDllLines;

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    or the more memory-efficient 
    chomp(@exeDllLines);

my @dllarray;
foreach (@exeDllLines) {
   push @dllarray, $_ if /\.(?:dll|exe)$/i;
}

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    Update: Oops, not quite. I didn't see the square brackets around DLLs.

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