On Jun 17, 11:07 am, "Leo Jay" <[EMAIL PROTECTED]> wrote: > On Tue, Jun 17, 2008 at 11:29 AM, pirata <[EMAIL PROTECTED]> wrote: > > I'm a bit confusing about whether "is not" equivelent to "!=" > > > if a != b: > > ... > > > if a is not b: > > ... > > > What's the difference between "is not" and "!=" or they are the same thing? > > The 'is' is used to test do they point to the exactly same object. > The '==' is used to test are their values equal. > > same objects are equal, but equal don't have to be the same object. > > and be very careful to the dirty corner of python:
No you don't have to be careful, you should never rely on it in the first place. Basically 'a is b' and 'not(a is b)' is similar to 'id(a) == id(b)' and 'not(id(a) == id(b))' You use 'is' when you want to test whether two variable/names are actually the same thing (whether they actually refers to the same spot on memory). The '==' equality comparison just test whether two objects' values can be considered equal. -- http://mail.python.org/mailman/listinfo/python-list
