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

All, is there any way to print all the elements of any array instead of referencing each element like so [0] 1 2 ...etc? I was thinking something like * here is my code 

use strict;
open (FH,"/usr/local/bin/perld/derektapes") or die "cannot open FH: $!
+ \n";
my @a=();
my $i=0;
my $ct=0;
my $or_string=" or ";
my $w_param="-w '";
my $b_param="barcode=";
while (<FH>) {
        chomp $_;
        $a[$i]=$_;
        $i++;
}

                print $w_param; print $b_param; print $a[0];

[download]

Replies are listed 'Best First'.
Re: printing all elements of arrays
by Fletch (Bishop) on Jul 13, 2004 at 01:06 UTC

    perldoc perlsyn, look for foreach. See also the entries for $" and $, in perldoc perlvar and perldoc -f join.

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Re: printing all elements of arrays
by FoxtrotUniform (Prior) on Jul 13, 2004 at 01:06 UTC
    (I)s there any way to print all the elements of any array instead of referencing each element like so [0], [1], [2] ...etc?

    If you want to print out each element of an array on its own line, 

    print join("\n", @array), "\n";

    [download]
    is probably the easiest way to do it. If the extra "\n" offends you, 
    print map {$_ . "\n"} @array;

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    will do much the same thing, but it's less idiomatic (I think).

    --
    F o x t r o t U n i f o r m
    Found a typo in this node? /msg me
    % man 3 strfry

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      I like print join("\n", @array, ""), myself.
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[d/l]
      what does the print map state? what perldoc can I read about the map call?
[reply]
        what does the print map state?

        Okay, 

        print join("\n", @array), "\n";

        [download]
        says "Stick a newline between each element in @array, return that as a string, print it, and print a newline at the end." On the other hand, 
        print map {$_ . "\n"} @array;

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        says "Build a list whose elements are the elements of @array with "\n" appended to them, then print that list."

        what perldoc can I read about the map call?

        You can read about any function with perldoc -f func_name.

        --
        F o x t r o t U n i f o r m
        Found a typo in this node? /msg me
        % man 3 strfry

[reply]
[d/l]
[select]
        perldoc -f map.

        map is a list-transformer; you give it a block of code and a list, and it applies the code to each element of the list, and returns a list made up of what the code returned for each element.

[reply]
        You can read perlfunc to find out about map. Also, the easiest way to print all the elements of an array is:

        print "@array\n";

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Re: printing all elements of arrays
by graff (Chancellor) on Jul 13, 2004 at 01:31 UTC
    This part of your code: 
    while (<FH>) {
   chomp $_;
   $a[$i]=$_;
   $i++;
}

    [download]
    Can be rendered in a variety of briefer ways, briefest of which is probably: 
    @a = <FH>;  # diamond operator in "list" (or array) context
            # will read all input records into array elements
chomp @a;   # chomp can work on a list

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    If there are other things you want to do while assigning input records to an array, you can keep the while loop, but without using the array index variable ($i): 
    while (<FH>) {
   chomp;        # $_ is the default arg to chomp;
     # ... do other things to $_ if necessary ...

   push @a, $_;  # add a new element at end of @a
}

    [download]
    In terms of printing the array elements as a "joined set", you should just play with different things to see how they work -- try a few command lines like this: 
     perl -e '@a=qw/one two three four/; print @a,$/'

 perl -e '@a=qw/one two three four/; print "@a$/"'

 perl -e '@a=qw/one two three four/; print join(" ", map { "foo=$_" } 
+@a), $/'

    [download]
    R some more FMs and have fun with it.
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Re: printing all elements of arrays
by Gunth (Scribe) on Jul 13, 2004 at 04:43 UTC 
    $, = "\t";
print @array;
#or
print shift . "\t" while @array;
#or
print $_    . "\t" for   @array;
#or
print map { $_ . "\t" } @array;
#or
print join("\t", @array);

    [download]
    TMTOWTDI. I would chose the first way if it were the only print in that scope. If not, I would chose the second.
    -Will
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Re: printing all elements of arrays
by pbeckingham (Parson) on Jul 13, 2004 at 03:30 UTC
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Re: printing all elements of arrays
by ysth (Canon) on Jul 13, 2004 at 01:23 UTC
    Perl has lots of different ways to handle arrays. Can you explain better what output you are actually looking for?
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