Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > Perl > Perl Misc > FAQ 4.49 How do I process/modify each element of an array?

Reply
Thread Tools

FAQ 4.49 How do I process/modify each element of an array?

 
 
PerlFAQ Server
Guest
Posts: n/a
 
      03-24-2011
This is an excerpt from the latest version perlfaq4.pod, which
comes with the standard Perl distribution. These postings aim to
reduce the number of repeated questions as well as allow the community
to review and update the answers. The latest version of the complete
perlfaq is at http://faq.perl.org .

--------------------------------------------------------------------

4.49: How do I process/modify each element of an array?

Use "for"/"foreach":

for (@lines) {
s/foo/bar/; # change that word
tr/XZ/ZX/; # swap those letters
}

Here's another; let's compute spherical volumes:

for (@volumes = @radii) { # @volumes has changed parts
$_ **= 3;
$_ *= (4/3) * 3.14159; # this will be constant folded
}

which can also be done with "map()" which is made to transform one list
into another:

@volumes = map {$_ ** 3 * (4/3) * 3.14159} @radii;

If you want to do the same thing to modify the values of the hash, you
can use the "values" function. As of Perl 5.6 the values are not copied,
so if you modify $orbit (in this case), you modify the value.

for $orbit ( values %orbits ) {
($orbit **= 3) *= (4/3) * 3.14159;
}

Prior to perl 5.6 "values" returned copies of the values, so older perl
code often contains constructions such as @orbits{keys %orbits} instead
of "values %orbits" where the hash is to be modified.



--------------------------------------------------------------------

The perlfaq-workers, a group of volunteers, maintain the perlfaq. They
are not necessarily experts in every domain where Perl might show up,
so please include as much information as possible and relevant in any
corrections. The perlfaq-workers also don't have access to every
operating system or platform, so please include relevant details for
corrections to examples that do not work on particular platforms.
Working code is greatly appreciated.

If you'd like to help maintain the perlfaq, see the details in
perlfaq.pod.
 
Reply With Quote
 
 
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Re: How include a large array? Edward A. Falk C Programming 1 04-04-2013 08:07 PM
FAQ 6.14 How do I process each word on each line? PerlFAQ Server Perl Misc 0 04-08-2011 04:00 AM
FAQ 6.14 How do I process each word on each line? PerlFAQ Server Perl Misc 0 01-26-2011 11:00 PM
FAQ 4.49 How do I process/modify each element of an array? PerlFAQ Server Perl Misc 0 01-21-2011 05:00 AM
Array#each - getting each element and the index Pat Maddox Ruby 6 01-20-2006 04:04 PM



Advertisments