foreach in array

loop362 has asked for the wisdom of the Perl Monks concerning the following question:

Aloha, I am trying to iterate through a simple array of 5 lines (read from a text file). I know the array always starts with 0. So when using the for each loop it skips 0. Why? This makes it leave out the first line, I only get 4 lines. I need to use PERL more often! I use BBEdit. I just opened my names.txt in Firefox also confirming 5 names. and added print scalar of @data.

foreach $name (@data) {
    print "$name";
}
[download]

#!/usr/bin/perl
use strict;
use warnings;
my @data;
my $name;
open (JOE, "</Users/mrg/Desktop/names.txt") or die "No can!";
while (<JOE>) {
@data = <JOE>;
}
foreach $name (@data) {
    print "$name";
}
[download]

This is names.txt

Joseph.Guillaume
Fred.Flintsone
Barney.Rubble
George.Jetson
ElRoy.Jetson
[download]

This is the Ouput:

Last login: Wed Jul 23 13:44:11 on ttyp1
Welcome to Darwin!
G4-2:~ mrg$ /var/tmp/folders.507/Cleanup\ At\ Startup/test-238549606.0
+74.pl.command; exit
Fred.Flintsone
Barney.Rubble
George.Jetson
ElRoy.Jetsonlogout
[Process completed]
[download]

Problem solved! by injunjoe Mahalo (Thank You)

Comment on foreach in array Select or Download Code

Replies are listed 'Best First'.
Re: foreach in array by injunjoel (Priest) on Jul 24, 2008 at 00:04 UTC
Greetings, I would suspect its a problem with how you are reading the lines in... try this `while(<JOE>){ push @data,$_; }` [download] rather than `while(<JOE>){ @data = <JOE>; }` [download] I think the while is shifting off the first element and thus you are getting what is left in @data. -InjunJoel "I do not feel obliged to believe that the same God who endowed us with sense, reason and intellect has intended us to forego their use." -Galileo	[reply] [d/l] [select]
Re^2: foreach in array by wade (Pilgrim) on Jul 24, 2008 at 00:13 UTC
++injunjoel, I was going to point this (the double use of `<JOE>`) out if you hadn't. -- Wade	[reply] [d/l]
Re: foreach in array by broomduster (Priest) on Jul 24, 2008 at 00:20 UTC
The "problem" here is that the diamond operator consumes one line of input. So the line `while (<JOE>) {` [download] eats the first line of the input file, but doesn't save it anywhere. You either want just `my @data = <JOE>;` [download] or `my @data; while (<JOE>) { push @data, $_; }` [download] and yes, yes, yes, always `use strict; use warnings;` [download]	[reply] [d/l] [select]
Re: foreach in array by ikegami (Patriarch) on Jul 23, 2008 at 23:34 UTC
You must be mistaken about the contents of your array. `foreach` doesn't skip elements. `my @data = qw( foo bar baz moo mar ); print("1st - 0 - $data[0]\n"); print("5th - 4 - $data[4]\n"); print("\n"); foreach $name (@data) { print "$name\n"; }` [download] `1st - 0 - foo 5th - 4 - mar foo bar baz moo mar` [download] A good way of determining the contents of an arbitrarily complex data structure (or a simple array) is to use Data::Dumper. `use Data::Dumper; my @data = qw( foo bar baz moo mar ); print(Dumper(\@data));` [download] `$VAR1 = [ 'foo', 'bar', 'baz', 'moo', 'mar' ];` [download] By the way, the language is called "Perl", not "PERL".	[reply] [d/l] [select]
Re: foreach in array by Joost (Canon) on Jul 23, 2008 at 23:35 UTC
You're making the assumption that your code skips the first element in the array. That assumption is wrong (very probably). For example: `my @data = (0, 1, 2, 3, 4); # 5 elements foreach my $name (@data) { print "$name\n"; }` [download] output: `0 1 2 3 4` [download] I suggest you use warnings, strict and/or post more of your code because the problem isn't in this part of your program. "What should it profit a man, if he should win a flame war, yet lose his cool?"	[reply] [d/l] [select]
Re: foreach in array by GrandFather (Saint) on Jul 23, 2008 at 23:40 UTC
Indeed you do! For a start always use strictures (use strict; use warnings; - see The strictures, according to Seuss). You don't need to interpolate the string in print. If all you are doing is printing each "line" from @data then you can: `use strict; use warnings; my @data = ...; print for @data;` [download] foreach is a synonym for for. The code you show will print all the contents of @data. If it doesn't print what you expected than @data doesn't contain what you expected. Perl is environmentally friendly - it saves trees	[reply] [d/l]
Re: foreach in array by toolic (Bishop) on Jul 23, 2008 at 23:52 UTC
In addition to the advice you have already received, a quick way to verify that the number of elements in an array is what you expect it to be is to use scalar: `print scalar @data, "\n";` [download]	[reply] [d/l]
Re: foreach in array by linuxer (Curate) on Jul 23, 2008 at 23:35 UTC
check if @data really contains the expected number of elements. make sure that your printed output is distinct (maybe empty string or undef in element). make sure you use strict and warnings in your scripts `print "elements in \@data: ", scalar( @data ), $/; foreach my $name ( @data ) { print "<$name>"; }` [download] update: quoted @. Thanks GrandFather	[reply] [d/l]
Re^2: foreach in array by GrandFather (Saint) on Jul 23, 2008 at 23:59 UTC
You probably meant to quote the @: `print "elements in \@data: ", scalar( @data ), $/;` [download] Perl is environmentally friendly - it saves trees	[reply] [d/l]