<数据>防止foreach循环被执行，为什么？ :)

问题描述

我有两个嵌套的foreach循环。如果我使用下面的代码：

$ $ $ $ $ $ $ $ $ $ $ $ foreach（@directories）{
my $ actual_directory = $ _;
打印\实际目录：。$ actual_directory。\\\
;

foreach（@files）{
my $ file_name = $ _;
my $ actual_file = $ actual_directory。$ file_name;
打印$ actual_file。\\\
;

打开（DATA，$ actual_file）或死Nelzeotevřítzdrojovýsoubor：$！\\\
;
my $ line_number = 0; （< DATA>）{
＃my @znaky = split（''，$ _）;

＃
＃my $ poradi = $ znaky [0]; #poradi nukleotidu
＃my $ hodnota = $ znaky [1]; #hodnota

＃my @temp = $ files_to_sum_of_lines {$ actual_file};
＃$ temp [$ line_number] + = $ hodnota;
＃$ files_to_sum_of_lines {$ actual_file} = @temp;

＃$ line_number + = 1;
＃}
＃close（DATA）;




$ b $我有这个输出：

  
除了不使用 DATA 使用词法循环变量和词法文件句柄。此外，Perl内置的 $。会记录您的行号。 
 
 
 为我的$ actual_directory（@directories）{
打印\实际目录：。$ actual_directory。\\\
; 
 
 foreach my $ file_name（@files）{
 my $ actual_file = $ actual_directory。$ file_name; 
打印$ actual_file。\\\
; 
 
打开我的$ INPUT，'<'，$ actual_file 
或者Nelzeotevřítzdrojovýsoubor：$！\\\
; 
 
 while（my $ line =< $ INPUT>）{
 my @znaky = split（''，$ line）; 
 my $ poradi = $ znaky [0]; #poradi nukleotidu 
 my $ hodnota = $ znaky [1]; #hodnota 
 @temp = $ files_to_sum_of_lines {$ actual_file}; 
 $ temp [$。 ] + = $ hodnota; 
 $ files_to_sum_of_lines {$ actual_file} = @temp; 
} 
 close $ INPUT; 
 
 
 
 
 $ b $ p 
 $ b $ p另一方面，如果在那里有逻辑错误。 
 
 $ p $ ＃！/ usr / bin / perl 
 
使用警告;严格使用
 
使用鲤鱼; 
使用File :: Find; 
使用File :: Spec :: Functions qw（catfile canonpath）; 
 
 my％counts; 
 find（\& count_lines_in_files，@ARGV）; 
 
 for my $ dir（sort keys％counts）{
 print$ dir\\\
; 
 my $ dircounts = $ counts {$ dir}; 
 for $ file（sort keys％{$ dircounts}）{
 printf\t％s：％d \\\
，$ file，$ dircounts-> {$ file}; 
} 
} 
 
 sub count_lines_in_files {
 my $ file = canonpath $ _; 
 my $ dir = canonpath $ File :: Find :: dir; 
 my $ path = canonpath $ File :: Find :: name; 
 
返回除非-f $路径; 
 
 $ counts {$ dir} {$ file} = count_lines_in_file（$ path）; 
} 
 
 sub count_lines_in_file {
 my（$ path）= @_; 
 
 my $ ret =打开我的$ fh，'<'，$ path; 
 
除非（$ ret）{
 carp无法打开'$ path'：$！; 
 return; 
} 
 1，而< $ fh>; 
 
 my $ n_lines = $ .; 
 
 close $ fh 
 or croak无法关闭'$ path'：$！; 
 
返回$ n_lines; 
} 
  
 
I have two nested foreach loops. If I use this code:
foreach (@directories) {
    my $actual_directory = $_;
    print "\nactual directory: ".$actual_directory."\n";

    foreach (@files) {
        my $file_name = $_;
        my $actual_file = $actual_directory.$file_name;
        print $actual_file."\n";

        open(DATA, $actual_file) or die "Nelze otevřít zdrojový soubor: $!\n";
        my $line_number = 0;

        #   while (<DATA>){
        #       my @znaky = split(' ',$_);
        #       my $poradi = $znaky[0]; #poradi nukleotidu
        #       my $hodnota = $znaky[1]; #hodnota

        #       my @temp = $files_to_sum_of_lines{$actual_file};
        #       $temp[$line_number] += $hodnota;
        #       $files_to_sum_of_lines{$actual_file} = @temp;

        #       $line_number+=1;
        #   }
        #   close(DATA);
    }
}
I got this output:
actual directory: /home/n/Plocha/counting_files/1/

/home/n/Plocha/counting_files/1/a.txt
/home/n/Plocha/counting_files/1/b.txt

actual directory: /home/n/Plocha/counting_files/2/

/home/n/Plocha/counting_files/2/a.txt
/home/n/Plocha/counting_files/2/b.txt
However, if I uncomment "while (<DATA>){ }", I loose a.txt and b.txt, so the output looks like this:
actual directory: /home/n/Plocha/counting_files/1/

/home/n/Plocha/counting_files/1/a.txt
/home/n/Plocha/counting_files/1/b.txt

actual directory: /home/n/Plocha/counting_files/2/

/home/n/Plocha/counting_files/2/
/home/n/Plocha/counting_files/2/
How can this while (<DATA>) prevent my foreach from being executed?Any help will be appreciated. Thanks a lot.
 解决方案 
In addition to not using DATA, try using lexical loop variables, and lexical filehandles. Also, Perl's built-in $. keeps track of line numbers for you.
for my $actual_directory (@directories) {
    print "\nactual directory: ".$actual_directory."\n";

    foreach my $file_name (@files) {
        my $actual_file = $actual_directory.$file_name;
        print $actual_file."\n";

        open my $INPUT, '<', $actual_file
            or die "Nelze otevřít zdrojový soubor: $!\n";

        while (my $line = <$INPUT>) {
               my @znaky = split(' ', $line);
               my $poradi = $znaky[0]; #poradi nukleotidu
               my $hodnota = $znaky[1]; #hodnota
               @temp = $files_to_sum_of_lines{$actual_file};
               $temp[ $. ] += $hodnota;
               $files_to_sum_of_lines{$actual_file} = @temp;
        }
        close $INPUT;
    }
}
On the other hand, I can't quite tell if there is a logic error in there. Something like the following might be useful:
#!/usr/bin/perl

use warnings; use strict;

use Carp;
use File::Find;
use File::Spec::Functions qw( catfile canonpath );

my %counts;
find(\&count_lines_in_files, @ARGV);

for my $dir (sort keys %counts) {
    print "$dir\n";
    my $dircounts = $counts{ $dir };
    for my $file (sort keys %{ $dircounts }) {
        printf "\t%s: %d\n", $file, $dircounts->{ $file };
    }
}

sub count_lines_in_files {
    my $file = canonpath $_;
    my $dir  = canonpath $File::Find::dir;
    my $path = canonpath $File::Find::name;

    return unless -f $path;

    $counts{ $dir }{ $file } = count_lines_in_file($path);
}

sub count_lines_in_file {
    my ($path) = @_;

    my $ret = open my $fh, '<', $path;

    unless ($ret) {
        carp "Cannot open '$path': $!";
        return;
    }
    1 while <$fh>;

    my $n_lines = $.;

    close $fh
        or croak "Cannot close '$path': $!";

    return $n_lines;
}
                        
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