use strict;
my $str = '+41 79 123 456 78
+417612345678
076 123 456 78
07812345678
7712345678
+41 47 123 456 78
+413212345678
021 123 456 78
02212345678
3412345678';
my $regex = qr/^\s*(\+[0-9][0-9]\s*|0|)(7.*)/mixp;
my $subst = '$2';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html