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How to check for an empty array in perl?

iphone
User

Dec 20, 2010, 11:20 PM

Post #1 of 4 (2683 views)

How to check for an empty array in perl?	Can't Post

Does the following work or is there a better way?

Code

		@array = {1,2,3}; 
			#print "ARRAY @array"; 
			if (!@array) { 
				 
				 
			} 
		foreach my $base_p4path (@array)#I want this for loop 
 to get executed only when @array has elements. 
{ 
}

(This post was edited by iphone on Dec 21, 2010, 12:21 AM)

shawnhcorey
Enthusiast

Dec 21, 2010, 6:43 AM

Post #2 of 4 (2673 views)

Re: [iphone] How to check for an empty array in perl? [In reply to]	Can't Post

If the array is empty, the loop is skipped:

Code

#!/usr/bin/perl 
 
use strict; 
use warnings; 
 
my @array = (); 
for my $item ( @array ){ 
  print "item = $item\n"; 
}

__END__

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iphone
User

Dec 21, 2010, 11:07 AM

Post #3 of 4 (2660 views)

Re: [shawnhcorey] How to check for an empty array in perl? [In reply to]	Can't Post

I should have been more specific.Basically I want to push $newfile to another array @newfiles only if the array is empty
and the instructions after the push instruction should not be executed.The following works for me but I want to know if there is a better way

Code

if{ 
			my $newfile="$file\n"; 
                        @array = grep(/\Q$newfile\E/,keys %hash); 
			if (!@array) 
			{ 
			 push @newfiles,$newfile; 
			 #last; 
			} 
			next unless (@array); 
                      ..................... 
}

rovf
Veteran

Dec 29, 2010, 4:00 AM

Post #4 of 4 (2440 views)

Re: [iphone] How to check for an empty array in perl? [In reply to]	Can't Post

I don't know what the 'next' is doing in your code, since you are not in a loop.

Quote

I want to push $newfile to another array @newfiles only if the array is empty

This could be done by

Code

push @newfiles,$newfile unless @array;

but you also say:

Quote

and the instructions after the push instruction should not be executed.

In this case, I think an 'if' is the cleanest solution:

Code

if(@array) { 
  ..... 
} else { 
  push @newfiles,$newfile; 
}

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