How can I read the lines of a file into an array in Perl? - perl

Question

I have a file named test.txt that is like this:
Test
Foo
Bar
But I want to put each line in a array and print the lines like this:
line1 line2 line3
But how can I do this?

Answer 1

#!/usr/bin/env perl
use strict;
use warnings;
my #array;
open(my $fh, "<", "test.txt")
or die "Failed to open file: $!\n";
while(<$fh>) {
chomp;
push #array, $_;
}
close $fh;
print join " ", #array;

Answer 2

Here is my single liner:
perl -e 'chomp(#a = <>); print join(" ", #a)' test.txt
Explanation:
read file by lines into #a array
chomp(..) - remove EOL symbols for each line
concatenate #a using space as separator
print result
pass file name as parameter

Answer 3

One more answer for you to choose from:
#!/usr/bin/env perl
open(FILE, "<", "test.txt") or die("Can't open file");
#lines = <FILE>;
close(FILE);
chomp(#lines);
print join(" ", #lines);

Answer 4

If you find yourself slurping files frequently, you could use the File::Slurp module from CPAN:
use strict;
use warnings;
use File::Slurp;
my #lines = read_file('test.txt');
chomp #lines;
print "#lines\n";

Answer 5

The most basic example looks like this:
#!/usr/bin/env perl
use strict;
use warnings;
open(F, "<", "test.txt") or die("Cannot open test.txt: $!\n"); # (1)
my #lines = ();
while(<F>) { chomp; push(#lines, $_); } # (2)
close(F);
print "#lines"; # (3) stringify
(1) is the place where the file is opened.
(2) File handles work nicely within list enviroments (scalar/list environments are defined by the left value), so if you assign an array to a file handle, all the lines are slurped into the array. The lines are delimited (ended) by the value of $/, the input record separator. If you use English;, you can use $IRS or $INPUT_RECORD_SEPARATOR. This value defaults to the newline character \n;
While this seemed to be a nice idea, I've just forgot the fact that if you print all the lines, the ending \n will be printed too. Baaad me.
Originally the code was:
my #lines = <F>;
instead of the while loop. This is still a viable alternative, but you should swap (3) with chomping and then printing/stringifying all the elements:
for (#lines) { chomp; }
print "#lines";
(3) Stringifying means converting an array to a string and inserting the value $" between the array elements. This defaults to a space.
See: the perlvar page.
So the actual 2nd try is:
#!/usr/bin/env perl
use strict;
use warnings;
open(F, "<", "test.txt") or die("Cannot open test.txt: $!\n"); # (1)
my #lines = <F>; # (2)
close(F);
chomp(#lines);
print "#lines"; # (3) stringify

Answer 6

This is the simplest version I could come up with:
perl -l040 -pe';' < test.txt
Which is roughly equivalent to:
perl -pe'
chomp; $\ = $/; # -l
$\ = 040; # -040
'
and:
perl -e'
LINE:
while (<>) {
chomp; $\ = $/; # -l
$\ = " "; # -040
} continue {
print or die "-p destination: $!\n";
}
'

Answer 7

This is the code that do this (assume the below code inside script.pl) :
use strict;
use warnings
my #array = <> ;
chomp #array;
print "#array";
It is run by:
scirpt.pl [your file]