One of the reasons that students want to apply for studying in Canada is for the opportunity to work after graduation and then if desired obtain permanent residency in Canada. The Canadian government has no problems with dual intent as long as the student’s first intent is to upgrade their current academic status so they can be more gainfully employed either in their homeland or in Canada.
There is lots of information available on the Government of Canada’s websites directed to students who want to study in Canada.
This site not only states how long a student can work after graduating, depending on how long their study program is, but it also addresses the issue of a student taking a one year degree and then applying for a diploma in Canada and how that benefits them with the available work programs.
I could explain it all here in this article but sometimes it is best to read it directly from the site itself: http://www.cic.gc.ca/english/resources/manuals/bulletins/2010/ob194.asp.