Re^2: What is the scope of $

If all the OP's examples use the global $_ then printing it at the end would show the last value assigned. What actually happens is a warning for 'Use of uninitialized value $_ ...' The subroutine uses whatever $_ that is in scope when it is called.

use warnings;
use strict;

sub abc()
{
  $_ = 'x';
}

foreach(1..2)
{
    my $loopvar = 'in the loop';
  print "Before:$_\n";
  abc();
  print "After:$_\n";
}

print "\$_ = $_\n";  # warning for uninitialized value $_ (global scop
+e)

abc();
print "\$_ = $_\n";  # prints $_ = x
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Re^3: What is the scope of $_? by tobyink (Canon) on Nov 26, 2012 at 23:16 UTC
As I said, all the OP's examples use the global `$_` but some Perl control structures localize that variable. The same effect is illustrated here using global `$::x`... `use warnings; use strict; sub abc() { $::x = 'x'; } foreach $::x (1..2) { print "Before:$::x\n"; abc(); print "After:$::x\n"; } print "\$::x = $::x\n"; # warning for uninitialized value $x (global +scope) abc(); print "\$::x = $::x\n"; # prints $x = x` [download] `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]
Re^4: What is the scope of $_? by Lotus1 (Vicar) on Nov 27, 2012 at 13:49 UTC
So when the foreach loop finishes it restores the undef value to $_. Thanks.	[reply]