1. The Padre is Perl IDE and very convenience to learn and debug on MS OS,
The link http://padre.perlide.org/howto.html tell us sth about Padre.
2. what is different between Double quotes " " and Single quotes ' ' ？
Escape character work in " ",but not in ' '. Single quote' ' -->what input,what output.
If quote is not specify,it influence by later.