Vamsi Pavan’s Place

Perl offers several different ways to include code from one file
into another. Here are the deltas between the various inclusion
constructs:
1) do $file is like eval `cat $file`, except the former:
1.1: searches @INC and updates %INC.
1.2: bequeaths an *unrelated* lexical scope on the eval’ed code.
2) require $file is like do $file, except the former:
2.1: […]

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Alias of perl builtin variables
==========================================================
use English
The English module provides aliases for the Perl builtin variables. $ARG is equivalent to $_
$1 equivalent to $MATCH
$` equivalent to $PREMATCH
$’ equivalent to $POSTMATCH
Locate the source path of a perl script during run time
============================================
use FindBin;
$FindBin::Bin

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#!/usr/bin/perl
print “Hey! “, mysub(”foo”);
sub mysub {
my $a=shift;
print “$a “;
}
It outputs: foo Hey! 1
Because print evaluates its rightmost terms first, the “mysub()” is called before the “Hey! ” is printed. That prints “foo” and returns a value of “1″. The “Hey !” is evaluated and printed, and then […]

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#!/usr/bin/perl
my ($x,$a)=(0,1);
if ($a || $x++) {
print “foo\n”;
}
print “$x”;
At last, it will print 0 because, during the evaluation of if statement, since $a = 1, the next part of ‘or’ wont be evaluated. So $x will still remain 0.

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#!/usr/bin/perl
@list=qw(one two three);
foreach(reverse @list) {
print “$_\n”;
$_=”foo”;
}
print “$list[0]\n”;
Finally it will pring ‘foo’ not ‘one’. Because
$_ isn’t a copy of the list element, it’s a reference. Modifying it will change the list.

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