It depends on which country you are from, and which province you're in (they administer their own road rules). You may not need an IDP if your home country licence is readable by Canadian authorities (ie in English or French) and clearly states what type of vehicle you're licensed to drive. So it's unclear if a license that says "Class C" is sufficient unless the licence specifies what Class C means. To be on the safe side, get an IDP anyway - they are recognised in Canada. In some provinces where driving on your home country license is allowed, you can do so for 90 days, but if you have an IDP that extends to 1 year.
Phil at the safety hub. almost 6 years ago