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
This question is related to
python
math
syntax
operators
floor-division
>>> print 5.0 / 2
2.5
>>> print 5.0 // 2
2.0
The double slash, //, is floor division:
>>> 7//3
2
// is floor division, it will always give you the floor value of the result./ is the floating-point division.Followings are the difference between / and //;
I have run these arithmetic operations in Python 3.7.2
>>> print (11 / 3)
3.6666666666666665
>>> print (11 // 3)
3
>>> print (11.3 / 3)
3.7666666666666667
>>> print (11.3 // 3)
3.0
The above answers are good. I want to add another point. Up to some values both of them result in the same quotient. After that floor division operator (//) works fine but not division (/) operator.
- > int(755349677599789174/2)
- > 377674838799894592 #wrong answer
- > 755349677599789174 //2
- > 377674838799894587 #correct answer
// implements "floor division", regardless of your type. So
1.0/2.0 will give 0.5, but both 1/2, 1//2 and 1.0//2.0 will give 0.
See https://docs.python.org/whatsnew/2.2.html#pep-238-changing-the-division-operator for details
Python 2.7 and other upcoming version of python:
/)Divides left hand operand by right hand operand
Example: 4 / 2 = 2
//)The division of operands where the result is the quotient in which the digits after the decimal point are removed. But if one of the operands is negative, the result is floored, i.e., rounded away from zero (towards negative infinity):
Examples: 9//2 = 4 and 9.0//2.0 = 4.0, -11//3 = -4, -11.0//3 = -4.0
Both / Division and // floor division operator are operating in similar fashion.
The double slash, //, is floor division:
>>> 7//3
2
// implements "floor division", regardless of your type. So
1.0/2.0 will give 0.5, but both 1/2, 1//2 and 1.0//2.0 will give 0.
See https://docs.python.org/whatsnew/2.2.html#pep-238-changing-the-division-operator for details
// is floor division, it will always give you the integer floor of the result. The other is 'regular' division.
>>> print 5.0 / 2
2.5
>>> print 5.0 // 2
2.0
The double slash, //, is floor division:
>>> 7//3
2
Python 3.x Clarification
Just to complement some previous answers.
It is important to remark that:
a // b
Is floor division. As in:
math.floor(a/b)
Is not int division. As in:
int(a/b)
Is not round to 0 float division. As in:
round(a/b,0)
As a consequence, the way of behaving is different when it comes to positives an negatives numbers as in the following example:
1 // 2 is 0, as in:
math.floor(1/2)
-1 // 2 is -1, as in:
math.floor(-1/2)
The double slash, //, is floor division:
>>> 7//3
2
The answer of the equation is rounded to the next smaller integer or float with .0 as decimal point.
>>>print 5//2
2
>>> print 5.0//2
2.0
>>>print 5//2.0
2.0
>>>print 5.0//2.0
2.0
5.0//2 results in 2.0, and not 2 because the return type of the return value from // operator follows python coercion (type casting) rules.
Python promotes conversion of lower datatype (integer) to higher data type (float) to avoid data loss.
To clarify for the Python 2.x line, / is neither floor division nor true division.
/ is floor division when both args are int, but is true division when either of the args are float.
/ --> Floating point division
// --> Floor division
Lets see some examples in both python 2.7 and in Python 3.5.
Python 2.7.10 vs. Python 3.5
print (2/3) ----> 0 Python 2.7
print (2/3) ----> 0.6666666666666666 Python 3.5
Python 2.7.10 vs. Python 3.5
print (4/2) ----> 2 Python 2.7
print (4/2) ----> 2.0 Python 3.5
Now if you want to have (in python 2.7) same output as in python 3.5, you can do the following:
Python 2.7.10
from __future__ import division
print (2/3) ----> 0.6666666666666666 #Python 2.7
print (4/2) ----> 2.0 #Python 2.7
Where as there is no differece between Floor division in both python 2.7 and in Python 3.5
138.93//3 ---> 46.0 #Python 2.7
138.93//3 ---> 46.0 #Python 3.5
4//3 ---> 1 #Python 2.7
4//3 ---> 1 #Python 3.5
The above answers are good. I want to add another point. Up to some values both of them result in the same quotient. After that floor division operator (//) works fine but not division (/) operator.
- > int(755349677599789174/2)
- > 377674838799894592 #wrong answer
- > 755349677599789174 //2
- > 377674838799894587 #correct answer
5.0//2 results in 2.0, and not 2 because the return type of the return value from // operator follows python coercion (type casting) rules.
Python promotes conversion of lower datatype (integer) to higher data type (float) to avoid data loss.
/ --> Floating point division
// --> Floor division
Lets see some examples in both python 2.7 and in Python 3.5.
Python 2.7.10 vs. Python 3.5
print (2/3) ----> 0 Python 2.7
print (2/3) ----> 0.6666666666666666 Python 3.5
Python 2.7.10 vs. Python 3.5
print (4/2) ----> 2 Python 2.7
print (4/2) ----> 2.0 Python 3.5
Now if you want to have (in python 2.7) same output as in python 3.5, you can do the following:
Python 2.7.10
from __future__ import division
print (2/3) ----> 0.6666666666666666 #Python 2.7
print (4/2) ----> 2.0 #Python 2.7
Where as there is no differece between Floor division in both python 2.7 and in Python 3.5
138.93//3 ---> 46.0 #Python 2.7
138.93//3 ---> 46.0 #Python 3.5
4//3 ---> 1 #Python 2.7
4//3 ---> 1 #Python 3.5
// is floor division, it will always give you the floor value of the result./ is the floating-point division.Followings are the difference between / and //;
I have run these arithmetic operations in Python 3.7.2
>>> print (11 / 3)
3.6666666666666665
>>> print (11 // 3)
3
>>> print (11.3 / 3)
3.7666666666666667
>>> print (11.3 // 3)
3.0
// implements "floor division", regardless of your type. So
1.0/2.0 will give 0.5, but both 1/2, 1//2 and 1.0//2.0 will give 0.
See https://docs.python.org/whatsnew/2.2.html#pep-238-changing-the-division-operator for details
As everyone has already answered, // is floor division.
Why this is important is that // is unambiguously floor division, in all Python versions from 2.2, including Python 3.x versions.
The behavior of / can change depending on:
__future__ import or not (module-local)-Q old or -Q newPython 2.7 and other upcoming version of python:
/)Divides left hand operand by right hand operand
Example: 4 / 2 = 2
//)The division of operands where the result is the quotient in which the digits after the decimal point are removed. But if one of the operands is negative, the result is floored, i.e., rounded away from zero (towards negative infinity):
Examples: 9//2 = 4 and 9.0//2.0 = 4.0, -11//3 = -4, -11.0//3 = -4.0
Both / Division and // floor division operator are operating in similar fashion.
// is floor division, it will always give you the integer floor of the result. The other is 'regular' division.
The answer of the equation is rounded to the next smaller integer or float with .0 as decimal point.
>>>print 5//2
2
>>> print 5.0//2
2.0
>>>print 5//2.0
2.0
>>>print 5.0//2.0
2.0
// is floor division, it will always give you the integer floor of the result. The other is 'regular' division.
// implements "floor division", regardless of your type. So
1.0/2.0 will give 0.5, but both 1/2, 1//2 and 1.0//2.0 will give 0.
See https://docs.python.org/whatsnew/2.2.html#pep-238-changing-the-division-operator for details
As everyone has already answered, // is floor division.
Why this is important is that // is unambiguously floor division, in all Python versions from 2.2, including Python 3.x versions.
The behavior of / can change depending on:
__future__ import or not (module-local)-Q old or -Q newPython 3.x Clarification
Just to complement some previous answers.
It is important to remark that:
a // b
Is floor division. As in:
math.floor(a/b)
Is not int division. As in:
int(a/b)
Is not round to 0 float division. As in:
round(a/b,0)
As a consequence, the way of behaving is different when it comes to positives an negatives numbers as in the following example:
1 // 2 is 0, as in:
math.floor(1/2)
-1 // 2 is -1, as in:
math.floor(-1/2)
To clarify for the Python 2.x line, / is neither floor division nor true division.
/ is floor division when both args are int, but is true division when either of the args are float.
// is floor division, it will always give you the integer floor of the result. The other is 'regular' division.
Source: Stackoverflow.com