for my $dat1 (@data1) {
    for my $dat2 (@data2) {
        my $filename = "file_$dat1\_$dat2.txt";
        print "<$filename>\n";
        open my $fh, '<', $filename or die "a horrible death $!";
    }
}
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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I have tried that. The file names are printing properly. The variables themselves independently also looks fine when printed. Also I can open these files when I loop them directly using the array like.

open ( TEST, ">", "test.txt") or die "\n$!\n";
foreach my $var ( @file_list ) {
  print "\n$var\n";  
  open ( RL, "<", $var ) or die "\n$!\n";
  while (<RL>){
    print TEST $_;
  }  
}
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skooma:

You missed one bit that choroba put in his code: He wrapped the filename in brockets (<>) so that whitespace at the beginning or ending of the line would be more obvious. I expect that he's thinking your code would print something like:

<foo
>
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instead of the expected:

<foo>
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because you may have gotten your data from a file without remembering to chomp off the line endings.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Hello skooma,

choroba got in ahead of me, but another possibility is that your nested loops are generating more filenames than you actually have files. In the example given, your array @data1 will contain 1.1 and 1.2, and the array @data2 will contain 2.1 and 2.2. But your nested loops will then generate four file names:

file_1.1_2.1.txt
file_1.1_2.2.txt
file_1.2_2.1.txt
file_1.2_2.2.txt
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Do all of these files exist in the folder? If not, that would explain the “No such file” errors.

Hope that helps,

foreach my $dat1 (@data1){
  foreach my $dat2 (@data2){
    my $path = "file_$dat1\_$dat2.txt";
    open (FH, "<", $path) or die "Error opening '$path': '$!'";
    .....do something......
  }
}
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Opening and manipulating files within a loop that is also finding them can cause problems in some environments.

wat? examples please

It depends on the operating system, but a file-finder can skip file entries or see the same entry more than once ... a problem that is neatly avoided by completely scanning, say, a particular directory, then processing that list before moving on to the next one. (I have not looked closely at Perl's implementation of file-finders, but in other languages I noticed them doing this internally, and wondered why they did it that way.) Particularly if you are inserting, deleting, or renaming entries in the designated container, this approach can avoid a lot of messy problems.