This is a frequent pitfall

my $one = 1;
print "one $one\n";
if ( $one = 2){
   print "one $one\n";
   $one = 22;
} else {
   $one = 3;
}
print "one $one\n";
__END__
one 1
one 2
one 22
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Common Perl Pitfalls / perltrap

Tutorials: Basic debugging checklist , brian's Guide to Solving Any Perl Problem

perlintro, http://learn.perl.org/books/beginning-perl/, http://perl-tutorial.org/, Tutorials: Basic debugging checklist , brian's Guide to Solving Any Perl Problem, Modern Perl book, a loose description of how experienced and effective Perl 5 programmers work....You can learn this too.

The Perl Monks Guide to the Monastery