I'm running a script that extracts links from a webpage but the webpage outputs a different number of correct urls everytime something on the webpage changes, which happens very often for the purpose of this script. My 'constraint' is the $tco it makes sure that the urls onyl start with http://t.co
$tconike = (grep /$tco/, #links);
print "$tconike\n";
This determines the number of urls that satifsy my needs, this prints '2'.
my #found = (grep /$tco/, #links);
if (#found) {
for my $url (#found) {
print "$found[0]\n";
print "$found[1]\n";
}
}
This prints the accual urls in this case there is two. ex
http://t.co/5
http://t.co/r
Can I have the perl script recignize the number of urls starting with t.co and add more varaibles (the $found[0] and $found[1]) based on what $tconike (the number of useable urls) outputs?
I NEED TO ACCESS THE URLS LATER WHEN I USE WWW::Mechanize TO FILL OUT FORMS ON THE URLS.
As choroba said, you don't need to do that. You can just use print "$url\n" instead of each array element individually, because it will call the block of the loop for each element inside #found.
If you still want more variables based on the number of urls, you could do the following. But this is not code that you should use in production. In fact, don't use it. It works, but it's intended as a joke. :)
my $code;
my #found = (grep /$tco/, #links);
if (#found) {
for (my $i=0; $i<= $#found; $i++) {
$code .= q{print "$found[$i]\n"} . qq{\n};
}
eval $code for #found; # this is very evil
}
Related
Getting an error when I attempt to dump out part of a multi dimensional hash array. Perl spits out
Can't use string ("somedata") as an ARRAY ref while "strict refs" in use at ./myscript.pl
I have tried multiple ways to access part of the array I want to see but I always get an error. I've used Dumper to see the entire array and it looks fine.
#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper qw(Dumper);
use String::Util qw(trim);
my %arrHosts;
open(my $filehdl, "<textfile.txt") || die "Cannot open or find file textfile.txt: $!\n";
while( my $strInputline = <$filehdl> ) {
chomp($strInputline);
my ($strHostname,$strOS,$strVer,$strEnv) = split(/:/, $strInputline);
$strOS = lc($strOS);
$strVer = trim($strVer);
$strEnv = trim($strEnv);
$strOS = trim($strOS);
$arrHosts{$strOS}{$strVer}{$strEnv} = $strHostname;
}
# If you want to see the entire database, remove the # in front of Dumper
print Dumper \%arrHosts;
foreach my $machine (#{$arrHosts{solaris}{10}{DEV}}) {
print "$machine\n";
}
close($filehdl);
The data is in the form
machine:OS:OS version:Environment
For example
bigserver:solaris:11:PROD
smallerserver:solaris:11:DEV
I want to print out only the servers that are solaris, version 11, in DEV. Using hashes seems the easiest way to store the data but alas, Perl barfs when attempting to print out only a portion of it. Dumper works great but I don't want to see everything. Where did I go wrong??
You have the following:
$arrHosts{$strOS}{$strVer}{$strEnv} = $strHostname;
That means the following contains a string:
$arrHosts{solaris}{10}{DEV}
You are treating it as if it contains a reference to an array. To group the hosts by OS+ver+env, replace
$arrHosts{$strOS}{$strVer}{$strEnv} = $strHostname;
with
push #{ $arrHosts{$strOS}{$strVer}{$strEnv} }, $strHostname;
Iterating over #{ $arrHosts{solaris}{10}{DEV} } will then make sense.
My previous code also had the obvious problem whereby if the combo of OS, Version, and Environment were the same it wrote over previous data. Blunderful. Push is the trick
I am having problems trying to read an Outlook Email (Unicode) .msg file in Perl. Every other day i get an E-Mail with information which i have to put into another File. I'd like to automate this process.
Basically i have limited programming skills and have just started to learn Perl specifically for this task.
This is the part of my program trying to read the mail. So far did the Email::Outlook::Message from perlmonks get me:
use warnings;
use strict;
use Email::Outlook::Message;
use Email::MIME;
my $sourceDir = "c:/temp";
open_msg("test.msg");
sub open_msg {
my $verbose = 0;
my $msgFile = shift;
my $origMsg = new Email::Outlook::Message "$sourceDir/$msgFile", $verbose or die "$!";
my $mime = $origMsg->to_email_mime;
$mime->as_string;
return ($origMsg);
}
I am able to print the encoded hash, but i don't know how i can store the decoded text of the body in an array?
I am glad for every bit of help i can get.
Edit: i figured i change my initial question a bit to avoid posting a nearly equal question.
$mime->as_string returns the value you want to print, but you don't do anything with it, and then instead print the unchanged $mime handle. You want print $mime->as_string;
I believe the code should also display Useless use of as_string in void context or similar with use warnings;
I'm a beginner in programming, this is my first language. And in my class we are using a slightly out of date book to learn with (Book copyrighted '02). Doubt this would affect you helping me much, but worth noting.
The problem
I don't know how to format a simple foreach statement using/combined with an array. I'm getting mixed up and my book doesn't provide examples. I'm trying to get it so the Uses/Primary_Uses are shown when the user checks multiple checkboxes.
#!/usr/bin/perl
#c04ex5.cgi - creates a dynamic Web page that acknowledges
#the receipt of a registration form
print "Content-type: text/html\n\n";
use CGI qw(:standard -debug);
use strict;
#declare variables
my ($name, $serial, $modnum, $sysletter, $primary_uses, $use, #primary_uses, #uses);
my #models = ("Laser JX", "Laser PL", "ColorPrint XL");
my #systems = ("Windows", "Macintosh", "UNIX");
my #primary_uses = ("Home", "Business", "Educational", "Other");
#assign input items to variables
$name = param('Name');
$serial = param('Serial');
$modnum = param('Model');
$sysletter = param('System');
#primary_uses = param('Use');
#create Web page
print "<HTML><HEAD><TITLE>Juniper Printers</TITLE></HEAD>\n";
print "<BODY><H2>\n";
print "Thank you , $name, for completing \n";
print "the registration form.<BR><BR>\n";
print "We have registered your Juniper $models[$modnum] printer, \n";
print "serial number $serial.\n";
print "You indicated that the printer will be used on the\n";
print "$systems[$sysletter] system. <BR>\n";
print "The primary uses for this printer will be the following:\n";
#The part I'm having trouble with.
foreach $use (#primary_uses) {
print "$use [#use]<BR>\n";
}
print "</H2></BODY></HTML>\n";
My naming of variables might be a bit off, I was getting desperate and making sure I declare more than I should.
If you wanted to print a simple list of items, you should just use the $use variable:
foreach $use (#primary_uses) {
print "$use<BR>\n";
}
Note that this will also remove the fatal error that comes from not declaring #use. Perhaps that was also a point of confusion for you. $use and #use are two completely different variables, despite having the same name.
Note that you can print a list with the CGI module very easily:
my $cgi = CGI->new;
print $cgi->li(\#primary_uses);
Outputs the list interpolated in a list html entity, like so:
<li>Home</li> <li>Business</li> <li>Educational</li> <li>Other</li>
Some other pointers:
Note that it is a good idea to declare your variables in the smallest scope possible
foreach my $use (#primary_uses) { # note the use of "my"
print "$use<BR>\n";
}
That also goes with the other variables. A good idea is to declare them right as you initialize them:
my $name = param('Name');
Then people who read your code don't have to scan backwards in the file to see where the variable has "been" before.
Note that you should never, ever use the content of data from a web form without sanitizing it first, because it is a huge security risk, especially when you print it. It allows a web user to execute arbitrary code on your system.
You should know that for and foreach are aliases for the same function.
Also, you should always, always use warnings:
use warnings;
There really is no good reason to ever not turn warnings on.
foreach my $myuse (#primary_uses) {
print $myuse;
}
You need to declare the variable.
will the following code always work in perl ?
for loop iterating over #array {
# do something
if ($condition) {
remove current element from #array
}
}
Because I know in Java this results in some Exceptions, The above code is working for me for now, but I want to be sure that it will work for all cases in perl. Thanks
Well, it's said in the doc:
If any part of LIST is an array, foreach will get very confused if you
add or remove elements within the loop body, for example with splice.
So don't do that.
It's a bit better with each:
If you add or delete a hash's elements while iterating over it,
entries may be skipped or duplicated--so don't do that. Exception: In
the current implementation, it is always safe to delete the item most
recently returned by each(), so the following code works properly:
while (($key, $value) = each %hash) {
print $key, "\n";
delete $hash{$key}; # This is safe
}
But I suppose the best option here would be just using grep:
#some_array = grep {
# do something with $_
some_condition($_);
} #some_array;
I've been trying to write a script to pre-process some long lists of files, but I am not confident (nor competent) with Perl yet and am not getting the results I want.
The script below is very much work in progress but I'm stuck on the check for duplicates and would be grateful if anyone could let me know where I am going wrong. The block dealing with duplicates seems to be of the same form as examples I have found but it doesn't seem to work.
#!/usr/bin/perl
use strict;
use warnings;
open my $fh, '<', $ARGV[0] or die "can't open: $!";
foreach my $line (<$fh>) {
# Trim list to remove directories which do not need to be checked
next if $line =~ m/Inventory/;
# MORE TO DO
next if $line =~ m/Scanned photos/;
$line =~ s/\n//; # just for a tidy list when testing
my #split = split(/\/([^\/]+)$/, $line); # separate filename from rest of path
foreach (#split) {
push (my #filenames, "$_");
# print "#filenames\n"; # check content of array
my %dupes;
foreach my $item (#filenames) {
next unless $dupes{$item}++;
print "$item\n";
}
}
}
I am struggling to understand what is wrong with my check for duplicates. I know the array contains duplicates (uncommenting the first print function gives me a list with lots of duplicates). The code as it stands generates nothing.
Not the main purpose of my post but my final aim is to remove unique filenames from the list and keep filenames which are in duplicated in other directories.
I know that none of these files are identical but many are different versions of the same file which is why I'm focussing on filename.
Eg I would want an input of:
~/Pictures/2010/12345678.jpg
~/Pictures/2010/12341234.jpg
~/Desktop/temp/12345678.jpg
to give an output of:
~/Pictures/2010/12345678.jpg
~/Desktop/temp/12345678.jpg
So I suppose ideally it would be good to check for uniqueness of a match based on the regex without splitting if that is possible.
This below loop does nothing, because the hash and the array only contain one value for each loop iteration:
foreach (#split) {
push (my #filenames, "$_"); # add one element to lexical array
my %dupes;
foreach my $item (#filenames) { # loop one time
next unless $dupes{$item}++; # add one key to lexical hash
print "$item\n";
}
} # #filenames and %dupes goes out of scope
A lexical variable (declared with my) has a scope that extends to the surrounding block { ... }, in this case your foreach loop. When they go out of scope, they are reset and all the data is lost.
I don't know why you copy the file names from #split to #filenames, it seems very redundant. The way to dedupe this would be:
my %seen;
my #uniq;
#uniq = grep !$seen{$_}++, #split;
Additional information:
You might also be interested in using File::Basename to get the file name:
use File::Basename;
my $fullpath = "~/Pictures/2010/12345678.jpg";
my $name = basename($fullpath); # 12345678.jpg
Your substitution
$line =~ s/\n//;
Should probably be
chomp($line);
When you read from a file handle, using for (foreach) means you read all the lines and store them in memory. It is preferable most times to instead use while, like this:
while (my $line = <$fh>)
TLP's answer gives lots of good advice. In addition:
Why use both an array and a hash to store the filenames? Simply use the hash as your one storage solution, and you will automatically remove duplicates. i.e:
my %filenames; #outside of the loops
...
foreach (#split) {
$filenames{$_}++;
}
Now when you want to get the list of unique filenames, just use keys %filenames or, if you want them in alphabetical order, sort keys %filenames. And the value for each hash key is a count of occurrences, so you can find out which ones were duplicated if you care.