Count # lines in perl using wc

Question

This seems really simple but neither a google search nor a stackoverflow search turn anything up. Is there a reason people don't do it this way? Sorry if I'm missing something.

I tried

$B = `wc -l $fileB`;
print "$B\n";
@B_array = split /\s+/, $B; #try to split on whitespace
foreach my $item (@B_array) {
        print "$item\n";
}

but that doesn't split the output of wc -l for some reason.

What's your output look like? You can just use `split(' ', $B)`. — squiguy, Jun 06 '13 at 00:55

score 6 · Accepted Answer · answered Jun 06 '13 at 00:57

6

Your code works on my computer, perhaps this is one of the reasons people avoid using external tools. You can do this with native Perl of course:

my $lc = 0;
open my $file, "<", "input" or die($!);
$lc++ while <$file>;
close $file;
print $lc, "\n";

answered Jun 06 '13 at 00:57

perreal

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score 2 · Answer 2 · answered Jun 06 '13 at 00:55

2

This avoids the split problem, but using cat like this can be considered wasteful of resources.

$B = `cat $fileB | wc -l`;

cat filename | wc -l just produces a number of lines -- wc cannot get a file name as it is reading from a pipe into stdin.

Also @array=split ' ', $B will work for you.

answered Jun 06 '13 at 00:55

jim mcnamara

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How does using cat avoid the split problem? – squiguy Jun 06 '13 at 00:58
@squiguy, there is no filename in the wc output is why :) – perreal Jun 06 '13 at 00:58
1

@perreal That's true, just prints a number eh? – squiguy Jun 06 '13 at 00:59
It produces nnnnnn as output instead of nnnnnnn filename – jim mcnamara Jun 06 '13 at 00:59

Count # lines in perl using wc

2 Answers2