Re: split and uninitialized variables

You can do
my ($x, $y, $z) = ('', '', ''); ($x, $y, $z) = split(',', $_);
[download]
OR
my ($x, $y, $z) = map { $_ || '' } split(',', $_);
[download]
to ensure the variables are initialised.

Update: Oops! I really need a new brain.

use strict;
use warnings;

$_ = "a,0,b";
my ($x, $y, $z) = split(',', $_);
foreach ($x, $y, $z) { $_ = '' unless defined($_) }

print "x = $x\ny = $y\nz = $z\n";

__END__

x = a
y = 0
z = b
[download]

Comment on Re: split and uninitialized variables Select or Download Code

Replies are listed 'Best First'.
Re^2: split and uninitialized variables by ikegami (Patriarch) on Sep 03, 2004 at 11:31 UTC
Your first solution `my ($x, $y, $z) = ('', '', ''); ($x, $y, $z) = split(',', $_);` [download] won't work. Any values assigned in the first line will get overwritten in the second line: `$_ = 'a,b'; my ($x, $y, $z) = ('', '', ''); ($x, $y, $z) = split(',', $_); print(defined($z)?'defined':'undefined', "\n"); # prints undefined.` [download] Your second solution `my ($x, $y, $z) = map { $_ \|\| '' } split(',', $_);` erases any '0'. Try: `my ($x, $y, $z) = map { defined($_)?$_:'' } (split(',', $_))[0..2];` [download] Personally, I'd go with the simple `my ($x, $y, $z) = (split(',', $_), ('') x 3);` solution mentioned elsewhere. Update: Added missing `[0..2]` as pointed out by Roy Johnson. Thanks.	[reply] [d/l] [select]
Re^3: split and uninitialized variables by Roy Johnson (Monsignor) on Sep 03, 2004 at 12:09 UTC
Actually, the map solution doesn't work, because split doesn't return three elements, so you'd need to make it `my ($x, $y, $z) = map { defined($_) ? $_ : '' } (split(/,/, $_))[0..2] +;` [download] Caution: Contents may have been coded under pressure.	[reply] [d/l]
Re^2: split and uninitialized variables by Fletch (Bishop) on Sep 03, 2004 at 11:33 UTC
Your first one's not going to work. `main::(-e:1): 0 DB<1> $_ = "a,b" DB<2> x ($x,$y,$z) = ('default') x 3 0 'default' 1 'default' 2 'default' DB<3> x ($x,$y,$z) = split( ',', $_ ) 0 'a' 1 'b' 2 undef` [download]	[reply] [d/l]
Re^2: split and uninitialized variables by antirice (Priest) on Sep 03, 2004 at 11:33 UTC
Both methods have problems: `> perl -wl my ($x,$y,$z) = ('','',''); ($x,$y,$z) = split(',','a,b'); print "$x $y $z"; __END__ Use of uninitialized value in concatenation (.) or string at - line 3. a b > perl -wl my ($x, $y, $z) = map { $_ \|\| '' } split(',', 'a,0,b'); print "$x $y $z"; __END__ a b` [download] The second one is easily fixed with: `perl -wl my ($x, $y, $z) = map defined $_ ? $_ : '', (split(',', 'a,0,b'))[0..2 +]; print "$x $y $z"; __END__ a 0 b` [download] Update: Doh! Thanks !1 (silly lurker). antirice The first rule of Perl club is - use Perl The ith rule of Perl club is - follow rule i - 1 for i > 1	[reply] [d/l] [select]


We don't bite newbies here... much
	PerlMonks

Re: split and uninitialized variables

This is an archived low-energy page for bots and other anonmyous visitors. Please sign up if you are a human and want to interact.