What is the difference between '/' and '//' when used for division?

Ray picture Ray · Oct 8, 2008 · Viewed 562.9k times · Source

Is there a benefit to using one over the other? In Python 2, they both seem to return the same results:

>>> 6/3
2
>>> 6//3
2

Answer

Eli Courtwright picture Eli Courtwright · Oct 8, 2008

In Python 3.x, 5 / 2 will return 2.5 and 5 // 2 will return 2. The former is floating point division, and the latter is floor division, sometimes also called integer division.

In Python 2.2 or later in the 2.x line, there is no difference for integers unless you perform a from __future__ import division, which causes Python 2.x to adopt the 3.x behavior.

Regardless of the future import, 5.0 // 2 will return 2.0 since that's the floor division result of the operation.

You can find a detailed description at https://docs.python.org/whatsnew/2.2.html#pep-238-changing-the-division-operator