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Perl Function Array Arguement Passing

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# 1  
Old 03-26-2009
Perl Function Array Arguement Passing
Hi All,

I have some questions regarding array arguements passing for Perl Function.
If @array contains 2 items , arguements passing would be like Code_A.
But what if @array needs to add in more items, the rest of the code like $_[some number] will have to be modified as well (highlighted in red), which is very troublesome, just like in Code_B where 1 more item is added to @array. Is there an easier way to overcome this problem ?

Code_A
Code:
#!/usr/local/bin/perl

my @array = ( "AAA" , "BBB" );


Generic( @array , "WE" , "HIGH" , "DOWN" );


sub Generic {
	foreach my $file ( $_[0] , $_[1] ) {
		print "Now Processing $file ...\n";
	};

	print "$_[2]\n";
	print "$_[3]\n";
	print "$_[4]\n";

}

Code_B
Code:
#!/usr/local/bin/perl

my @array = ( "AAA" , "BBB" , "CCC");


Generic( @array , "WE" , "HIGH" , "DOWN" );


sub Generic {
	foreach my $file ( $_[0] , $_[1] , $_[2]) {
		print "Now Processing $file ...\n";
	};

	print "$_[3]\n";
	print "$_[4]\n";
	print "$_[5]\n";

}

Last edited by Raynon; 03-26-2009 at 10:56 PM..
# 2  
Old 03-27-2009
There is a couple of ways to tackle the problem. Keep in mind when you pass arguments to a function they all become one big list. So either you pass the strings as the first arguments and the array last:

Code:
Generic( "WE" , "HIGH" , "DOWN", @array);
sub Generic {
           my ($w, $h, $d,@t) = @_;
	foreach my $file (@t) {
		print "Now Processing $file ...\n";
	};

	print "$w\n";
	print "$h\n";
	print "$d\n";

}

or you pass a reference to the array (it can be anywhere in the argument list, I place it first here only as an example):

Code:
Generic( \@array, "WE" , "HIGH" , "DOWN");
sub Generic {
           my ($ref, $w, $h, $d) = @_;
	foreach my $file (@{$ref}) {
		print "Now Processing $file ...\n";
	};

	print "$w\n";
	print "$h\n";
	print "$d\n";

}

# 3  
Old 03-27-2009
Hi KevinDAC,

Thanks for the advice, but what's the below code trying to do ?
And what does @_ represent ?
And what if there are 2 array list ? Which method would be better ?

Code:
my ($w, $h, $d,@t) = @_;

# 4  
Old 03-27-2009
@_ is the automagically created array containing all calling parameters (the array that you use when you access $_[x]). And if there's more than one array to pass around, refs are definitely the way to go, unless you have some other way to discern one array from the other.
# 5  
Old 03-27-2009
Hi pludi,

Thanks for the guidance!
Smilie Smilie
# 6  
Old 03-27-2009
Quote:
Originally Posted by pludi
@_ is the automagically created array containing all calling parameters (the array that you use when you access $_[x]). And if there's more than one array to pass around, refs are definitely the way to go, unless you have some other way to discern one array from the other.
I agree with pludi. If you have more than one array, or even really just one array, use references as I showed in my other post. As far as @_ goes, he explained it well enough so I will leave it at that.
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