Re: Check for empty array
Yes you are right !! Thanx Dharmender Rai --- John W. Krahn [EMAIL PROTECTED] wrote: Dharmender rai wrote: You can use defined() function by checking for the first element. No, checking the first element of an array will tell you whether or not the first element of the array is defined, it will not tell you if the array is empty. John -- use Perl; program fulfillment -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] __ Do You Yahoo!? Everything you'll ever need on one web page from News and Sport to Email and Music Charts http://uk.my.yahoo.com -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Check for empty array
You can use defined() function by checking for the
first element.
#!/usr/bin perl
use strict;
use warnings;
my @arr=(); ## empty
my $ref=\@arr; ##
if(!defined ($ref-[0]) {
# do your work here
}
if (!define ($arr-[0]) {
# do your work
}
--- dan [EMAIL PROTECTED] wrote: or
if (!$array[0]) {
# it's empty
}
your choice :)
dan
Nikola Janceski [EMAIL PROTECTED]
wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
if(not @array){
# it's empty
}
-Original Message-
From: Bryan Harris [mailto:[EMAIL PROTECTED]]
Sent: Friday, October 04, 2002 11:58 AM
To: Beginners Perl
Subject: Check for empty array
What's the easiest way to check whether an array
is empty?
I'm really feeling like a beginner today...
- Bryan
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Re: Check for empty array
I just noticed this thread, so forgive me if someone has already mentioned
this, or if I'm missing the original point. I just saw some bad examples of
how to accomplish what the subject asks, and felt I should chime in.
The idiomatic method for checking if an array has elements is simply:
if (@array) { ... }
If you've stored an array reference, as in $ref = \@array, then dereference:
if (@$ref) { ... }
See perldoc perldata for help on dealing with data types, perldoc perlref
and perldoc perldsc for help on dealing with references.
Checking an individual element to see if an array is empty will not work.
One of the examples was:
if (!defined $ref-[0]) { ... }
Given:
@array = (undef, foo, bar);
$ref = \@array;
That test will return a false positive; defined($ref-[0]) will be false,
yet there are elements in @array, and by extension, @$ref.
Another of the examples was:
if (!$array[0]) { ... }
Given:
@array = (0, foo, bar);
That test will also return a false positive; $array[0] is false, yet there
are elements in @array.
Michael
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Re: Check for empty array
Dharmender rai wrote: You can use defined() function by checking for the first element. No, checking the first element of an array will tell you whether or not the first element of the array is defined, it will not tell you if the array is empty. John -- use Perl; program fulfillment -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: Check for empty array
if(not @array){
# it's empty
}
-Original Message-
From: Bryan Harris [mailto:[EMAIL PROTECTED]]
Sent: Friday, October 04, 2002 11:58 AM
To: Beginners Perl
Subject: Check for empty array
What's the easiest way to check whether an array is empty?
I'm really feeling like a beginner today...
- Bryan
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Re: Check for empty array
HANDLE_EMPTY() unless @array; James Gray On Friday, October 4, 2002, at 10:57 AM, Bryan Harris wrote: What's the easiest way to check whether an array is empty? I'm really feeling like a beginner today... - Bryan -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Check for empty array
Bryan Harris wrote:
What's the easiest way to check whether an array is empty?
An array in a scalar context returns the number of elements in the
array.
if ( @array == 0 ) { # explicit test for zero elements
unless ( @array ) { # implicit test for zero elements
John
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Re: Check for empty array
or
if (!$array[0]) {
# it's empty
}
your choice :)
dan
Nikola Janceski [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
if(not @array){
# it's empty
}
-Original Message-
From: Bryan Harris [mailto:[EMAIL PROTECTED]]
Sent: Friday, October 04, 2002 11:58 AM
To: Beginners Perl
Subject: Check for empty array
What's the easiest way to check whether an array is empty?
I'm really feeling like a beginner today...
- Bryan
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Re: Check for empty array
On Fri, 2002-10-04 at 10:21, [EMAIL PROTECTED] wrote:
or
if (!$array[0]) {
# it's empty
}
your choice :)
dan
not quite... try that on this array:
@array = qw(0 1 2 3 4 5 6);
jjv
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Re: Check for empty array
On Friday, October 4, 2002, at 11:21 AM, dan wrote:
or
if (!$array[0]) {
This tests for a true value in the first element of an array, not if
it's empty. This test will succeed for the list (undef, 1, 2, More
Data), which is definitely not empty.
# it's empty
}
your choice :)
dan
Nikola Janceski [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]
...
if(not @array){
# it's empty
}
-Original Message-
From: Bryan Harris [mailto:[EMAIL PROTECTED]]
Sent: Friday, October 04, 2002 11:58 AM
To: Beginners Perl
Subject: Check for empty array
What's the easiest way to check whether an array is empty?
I'm really feeling like a beginner today...
- Bryan
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