use strict;
my $str = 'есть значения к примеру 42.5 или 39.5 нужно оставить только цифры и точку';
my $regex = qr~[^0-9.]+~mp;
my $subst = '';
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