Include file data in Perl array

Question

I am trying to pass all the data from a file into a Perl array and then I am trying to use a foreach loop to process every string in the array. The problem is that the foreach instead of printing each individual line is printing the entire array.I am using the following script.

while (<FILE>) {
  $_ =~ s/(\)|\()//g;
  push @array, $_;
}

foreach $n(@array) {
  print "$n\n";
}

Say for example the data in the array is @array=qw(He goes to the school everyday) the array is getting printed properly but the foreach loop instead of printing every element on different line is printing the entire array.

I don't see how that loop would produce anything other than "He\ngoes\nto\nthe\nschool\everyday\n" given that @array. Any chance of getting a whole minimal script along with sample input and output? — mu is too short
– mu is too short, Commented Dec 14, 2011 at 6:38
@muistooshort is right.show your input file and the expected output file alongwith the script — yb007
– yb007, Commented Dec 14, 2011 at 6:49
@muistooshort check out the answer provided by me (or TLP), it will print "He\n\ngoes\n\nto\n\n ..." etc. — Filip Roséen
– Filip Roséen, Commented Dec 14, 2011 at 6:56
@nandini You know, if you are having problems expressing what you mean, a very simple way to do that is to show 1) What you expect, 2) What you actually get. — TLP
– TLP, Commented Dec 14, 2011 at 7:14
@nandini Please do not take my previous comment as an excuse to repeat the qw(He goes to the school) example. =) Because that is clearly false. Use your actual input/output. — TLP
– TLP, Commented Dec 14, 2011 at 7:24

TLP · Accepted Answer · 2011-12-14 07:21:38Z

0

After reading your comments, I am guessing that your problem is that your source file does not contain any newlines: I.e. the entire file is just one line. Some text editors just wrap the text without actually adding any line break characters.

There is no "solution" to that problem; You have to add line breaks where you want them. You could write a script to do it, but I doubt it would make much sense. It all depends on what you want to do with this text.

Here's my code suggestions for your snippet.

chomp(@array = <FILE>);
s/[()]//g for @array;
print "$_\n" for @array;

or

@array = <FILE>;
s/[()]//g for @array;
print @array;

Note that if you have a file from another filesystem, you may get \r characters left over at the end of your strings after chomp, causing the output to look corrupted, overwriting itself.

Additional notes:

(\)|\() is better written as a character class: [()].
@array = <FILE> will read the entire file into the array. No need to loop.
As shown in my examples, print can be assigned a list of items (e.g. an array) as arguments. And you can have a postfix loop to print sequentially.
With a (postfix) loop, all the loop elements are aliased to $_, which is a handy way to do substitutions on the array.

edited Dec 14, 2011 at 7:21

answered Dec 14, 2011 at 6:52

TLP

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7 Comments

nandini Over a year ago

My data file-------------------------------------------------------In recent years many risk factors for the development of breast cancer that are linked to estrogens have been identified, and roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, has been shown to be an efficient inhibitor of the proliferation of human breast cancer cells. Therefore, we have examined the possibility that interference with estrogen signaling.

TLP Over a year ago

@nandini Have you considered the possibility that your file does not contain any newlines? Some text processors just wrap text without actually adding line breaks.

nandini Over a year ago

So what could be the solution, I have copied the above data from literature

mu is too short Over a year ago

@nandini: Can you paste the data file into your question in a code block? The "no line breaks" guess sounds pretty good.

TLP Over a year ago

try cat file.txt to see exactly what you have in the file.

|

yb007 · Accepted Answer · 2011-12-14 10:16:21Z

0

Since the entire file is just one line.You can split the string on basis of whitespace and print every element of array in new line

use strict;
use warnings;

open(FILE,'YOURFILE' ) || die ("could not open");
my $line= <FILE>;
my @array = split ' ',$line;
foreach my $n(@array)
{
print "$n\n";
  }
close(FILE);

Input File

In recent years many risk factors for the development of breast cancer that .....

Output

In
recent
years
many
risk
factors
for
the
development
of
breast
cancer
that
.....

answered Dec 14, 2011 at 10:16

yb007

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1 Comment

yb007 Over a year ago

@nandini If it worked for you then formal way of appreciating in StackOverflow is to accept it as an answer :)

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