Explain $[

[raklet]

What is the special variable $[.

 

[KevinADC]

$[ Compliance

Short Name $[

Scope localize

Definition

This variable, which is usually set to a value of 0, represents the index of the first element in any array. Programmers who are used to using 1 as the index of the first element of an array could change the value of this variable to suit their preference.
Example

$[ = 1;
$_ = "AlphaBetaGamma";
$tmp = index($_,"Beta");
print "Beta located at: $tmp\n";
$[ = 0;
$_ = "AlphaBetaGamma";
$tmp = index($_,"Beta");
print "Beta located at: $tmp\n";

 

[PaulTEG]

In the "books", they basically say "You can change this, but don't", my guess is its gonna affect some of Perl's internals.

Thought about it when coming from VB(1 based vs 0 based arrays), but they seemed so nice about it, I didn't want to upset them, ;-)

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[1DMF]

Seems odd to even concidering changing the index default, once armed with the knowledge that PERL arrays start at zero, $#array gives you last index and $count = @array; gives number of index's in an array, you don't need to change anything , do you ?

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you.

 

[KevinADC]

It's just something there for programmrs to use if they need to. There probably never is a real need to use it though.

 

[PaulTEG]

changing $[ will upset the intended use of the index function if altered for example

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[ishnid]

It's fun for obfuscation too ;-)

my @array = qw/one two three four/;

print $array[$[],"\n";

 

[1DMF]

It's fun for obfuscation too

- can you say that in English please ishnid ;-)

"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you.

 

[PaulTEG]

print $array[$[],"\n";

== print $array[0]; but it doesn't look like that

http://en.wikipedia.org/wiki/Obfuscation

Paul
------------------------------------
Spend an hour a week on CPAN, helps cure all known programming ailments ;-)

 

[1DMF]

so it's good to do people's heads in when tring to read your code, is that what you mean - lol



"In complete darkness we are all the same, only our knowledge and wisdom separates us, don't let your eyes deceive you.