Perl newbie questions!

Shell Programming and Scripting
1

Hi,

So I started to learn perl a few days ago, and I have some problems...

One of my problems...

#!C:\Perl64\bin\perl.exe -w
use LWP::Simple;
print "Content-Type: Text/Plain\n\n";

sub pagelinks {
return @all = get($_[0]) =~ /href\s*=\s*"?([^"\s>]+)/gis;
}

@a = pagelinks("http://website.com");

foreach $key (@a){
    print $key."\n";
        
        
}

so I tried using some regex I usualy have used in php with preg_match but they don't seem to work. So I got the above regex after searching google..
and tbh I don't understand it..
What I understand from it : href followed by none or more whitespaces followed by = followed by none or more whitespaces followed by 0 or 1 " and afterwards... I don';t get it at all! it's really frustrating.

my second problem..

let's assume I have this array :
@horse = ("mdamdamad" , "asdasda" ,"asdasd" ,"a");
I want to delete the element which is equal to "a".

foreach $key (@horse){
if ($key == "a"){
delete $horse[$key];}
}

the above code doesn't seem to work.. it deletes the @horse[-2] value. I have also tryied using $key =~ /a/ and (grep $key eq "a",@horse). All have failed me.. any suggestions? please...

2

When you post perl code use the perl highlighter, not the php highlighter which can mangle some perl code.

Your shortcut character class in the regexp are wrong, the shortcut classes like a space need a backslash \s:

return @all = get($_[0]) =~ /href\s*=\s*"?([^\s>]+)/gis;

I don't know if that will make your code do anything useful but it at least corrects the mistake in the regex.

3 
$
$ perl -e '{@horse = ("mdamdamad", "asdasda", "asdasd", "a"); foreach $i (@horse) {pop @horse,$i if $i eq "a"} print "@horse"}'
mdamdamad asdasda asdasd$
$

tyler_durden

4

Sry about using perl code in the php code tag must of missed the <code> tag.

Anyway I know about escaping the metacharacters, and I did that, but dunno for what reason I copied it wrong, not sure. thx for pointing that out though :stuck_out_tongue:

One more question :
Afaik in a sub $_[0],$_[1] refers to the first and second parameter which was sent to the function (correct me if im wrong please). So for example I have

#!C:\Perl64\bin\perl.exe -w
print "Content-Type: Text-plain\n\n";

@horse = ("mdamdamad" , "asdasda" ,"asdasd" ,"a");

getindex ("asd",@horse);

sub getindex {
$string = $_[0];
@a = $_[1];
print $string."\n";
foreach $key (@a){
    print $key."\n";
}
}

the problem is that @a in getindex only gets the first value of @horse , and not the entire array. How do I manage to pass to it the whole array?
edit: i found out the answer I had to use @a= @_;

5 
#!C:\Perl64\bin\perl.exe -w
print "Content-Type: Text/plain\n\n";#<-- this is not necessary unless running as a CGI script

@horse = ("mdamdamad" , "asdasda" ,"asdasd" ,"a");

getindex ("asd",@horse);

sub getindex {
   ($string,@a) = @_;
   print $string."\n";
   foreach $key (@a){
      print $key."\n";
   }
}

You're going to want to learn how to use references in perl really quickly insterad of trying to pass mixed data types like int he code above. An example:

#!C:\Perl64\bin\perl.exe -w
print "Content-Type: Text/plain\n\n";

@horse = ("mdamdamad" , "asdasda" ,"asdasd" ,"a");

getindex ("asd",\@horse);

sub getindex {
   my ($string,$array_ref) = @_;
   print $string."\n";
   foreach $key (@{$array_ref}){
      print $key."\n";
   }
}

The first three tutorials on this page discuss references:

Tutorials - perldoc.perl.org

Also:

you will want to use "warnings" and "strict" pragmas and start declaring your variables properly when writing perl code.

#!C:\Perl64\bin\perl.exe
use warnings;
use strict;
print "Content-Type: Text/plain\n\n";

my @horse = ("mdamdamad" , "asdasda" ,"asdasd" ,"a");

getindex ("asd",\@horse);

sub getindex {
   my ($string, $array_ref) = @_;
   print $string."\n";
   foreach $key (@{$array_ref}){
      print $key."\n";
   }
}

Also, don't use $a and $b as private variables in your perl scripts. Perl uses them for sorting data.

The http header was also wrong, you had: Text-plain should be: Text/plain

6

thanks alot KevinADC your response was very helpful! :b: