Try inserting

use lib '..';
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new package1() doesn't look right. One would have expected something along my $obj1 = B::b->new();? Furthermore, unless b is a pragma, it is common to use capitalised module names (here: B::B, see perlmod).
But maybe this is just a problem of the example?

You need to add the full directory containing directory B to @INC:

• PERL5LIB
• lib
• -I

I am giving exact code and error
I have two folders one is hello and second one is myfolder. Both the folder are parallel like A and B
. Folder hello contains hello.pl and myfolder folder contains package1.pm
Both the folder are in eg folder
hello.pl
#!/usr/local/bin/perl
use Data::Dumper;
use eg::myfolder::package1;
print @INC;
my $package1 = new package1();
warn "package ".Dumper($package1);
my $prnt = package1::DESTROY();
print "$prnt";

package1.pm
package package1;
sub new {
my($class, $name) = @_; # Class name is in the first parameter
my $self = { name => $name }; # Anonymous hash reference holds instance attributes
bless($self, $class); # Say: $self is a $class return $self;
}

sub DESTROY {
return 'package2';
}
1;
Error :

Can't locate eg/myfolder/package1.pm in @INC (@INC contains: C:/Perl/site/lib C: /Perl/lib .) at hello.pl line 3. BEGIN failed--compilation aborted at hello.pl line 3.

Your 'package' name doesn't match your 'use', first of all.

use eg::myfolder::package1;
package package1;
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should be

use eg::myfolder::package1;
package eg::myfolder::package1;
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or

use package1;
package package1;
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In either case, you should either execute your script from within the parent directory of the first level of the package name, or have that directory in @INC (via -I, 'use lib', etc). The parent directory of "eg", or the parent directory of "package1" (myfolder), depending on the name you choose. 'print @INC' isn't helping because your script fails to compile, but Perl prints @INC helpfully in your compilation error anyway.

Writing Modules has a similar issue, with good references to go read on this topic and other issues you'll run into fairly quickly once you get past this one.

--Dave

Do not tell lies. You are not giving the exact code nor the exact error. You have "sanitised" both to the point that they do not provide the information we require to provide informed help that directly addresses the problem you are having. There are a multitude of possible mistakes that could result in the type of error you describe. While we can, and do, guess which mistakes are most likely, we can't give a definitive answer if you give us inaccurate fuzzy information.

Do you want help? If so, give us good information!

True laziness is hard work

I would also try

use lib "../B";
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And end up with programs that only work from B, and its sibling directories?

And end up with programs that only work from B, and its sibling directories?

From my reading of the OP's original post, he wanted a relative program and module structure. This works for an A sub dir holding the program Foo-use, and a parallel level module dir B, holding a module Foo1.pm. The relative nature of the directories means they can be installed anywhere together, and the module in B will be found.

Make 2 subdirs anywhere in an arbitrary directory, named A and B

In A, the program:

#!/usr/bin/perl
use lib "../B";
use Foo1 foo;
use Tk;  # put in to show that @inc is still working fine

foo();
print "Goodbye\n";
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In the parallel B module directory, the module Foo1.pm

#module Foo1.pm located in B

package Foo1;
require Exporter;
 
@ISA = qw|Exporter|;
@EXPORT_OK = qw|foo|;
 
sub foo
{
   print "Hello World, I'm here\n";
}
1;
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Run it:

$  ./A/Foo-use
 Hello World
 Goodbye
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---

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh