Questions tagged [floor-division]
48 questions
581
votes
16 answers
What is the difference between '/' and '//' when used for division?
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

Ray
- 187,153
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65
votes
3 answers
Two forward slashes in Python
I came across this sample of code from a radix sort:
def getDigit(num, base, digit_num):
# pulls the selected digit
return (num // base ** digit_num) % base
What does the // do in Python?

Biff
- 1,009
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18
votes
4 answers
Java - How to do floor division?
I know that in Python you can do floor division like this:
5 // 2 #2
The // is used for something totally different in Java. Is there any way to do floor division in Java?
user10654536
13
votes
1 answer
Weird result of floor division in numpy
I stumbled upon a floor division result of a np.float32 or np.float64 , which I do not understand
I'm using numpy 1.15.4 in Python 3.6.7
>>> import numpy as np
>>> np.float32(0)//1
-0.0
I know, that i can workaround by abs() and such, but why am I…

Michal
- 163
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11
votes
3 answers
What does the "variable //= a value" syntax mean in Python?
I came across with the code syntax d //= 2 where d is a variable. This is not a part of any loop, I don't quite get the expression.
Can anybody enlighten me please?

Chris
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9
votes
1 answer
How is floor division not giving result according to the documented rule?
>>> print (12//0.2)
59.0
>>> print(floor(12/0.2))
60
Why floor division is not working according to the rule in this case?
p.s. Here Python is treating 0.2 as 0.20000000001 in the floor division case
So
(12/0.2000000001) is resulting in…

Aashutosh Ranjan
- 303
- 1
- 7
9
votes
1 answer
Weird behaviour of division in python
I'm trying to solve this problem in hackerrank. At some point I have to check if a number divides n(given input) or not.
This code works perfectly well except one test case(not an issue):
if __name__ == '__main__':
tc = int(input().strip())
…

Bharat
- 1,044
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9
votes
5 answers
Fast floor of a signed integer division in C / C++
In C a floor division can be done, eg:
int floor_div(int a, int b) {
int d = a / b;
if (a < 0 != b < 0) { /* negative output (check inputs since 'd' isn't floored) */
if (d * a != b) { /* avoid modulo, use multiply instead */
…

ideasman42
- 42,413
- 44
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4
votes
0 answers
What is the value of 5.5//1.1 in python? and How?
What's the step by step answer for 5.5//1.1.
While running in compiler it gives 4.0 as an answer.

Vasukipriya K N
- 53
- 5
3
votes
2 answers
How to divide a 128-bit dividend by a 64-bit divisor, where the dividend's bits are all 1's, and where I only need the 64 LSBs of the quotient?
I need to calculate (2128 - 1) / x. The divisor, x, is an unsigned 64-bit number. The dividend is composed of two unsigned 64-bit numbers (high and low), where both numbers are UINT64_MAX. I can only use 64-bit arithmetic and need it to be portable…

tgonzalez89
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3
votes
2 answers
Floor division // vs int() rounded off
I am a new user to Python 3.6.0. I am trying to divide 2 numbers that produces a big output. However, using
return ans1 // ans2
produces 55347740058143507128 while using
return int(ans1 / ans2)
produces 55347740058143506432.
Which is more accurate…

GordonJun
- 35
- 4
2
votes
0 answers
Why does numpy floor_divide with infinity differ from true_divide
numpy's floor division seems counterintuitive when dealing with np.inf. I feel like the answer should be same as true division in these examples
>>> -7 // np.inf
-1.0
>>> -7 / np.inf
-0.0
>>> np.inf // 7
nan
>>> np.inf / 7
inf
In my head, an…

pierce314159
- 21
- 2
2
votes
0 answers
np.floor_divide with 0 as denominator - no error on Mac
np.floor_divide(1.0,0)
results inf with RuntimeWarning: divide by zero encountered in floor_divide np.floor_divide(1.0,0) on Linux but results nan on Mac with no warning/error.
Why this difference on Mac and Linux ?

Noushadali
- 41
- 5
2
votes
0 answers
Python Double Forward Slash Difference from Floor
I'm using Python3 and getting different results when using // versus math.floor (other than return types).
My problem:
print('Using //: ', 1.0 // 0.2)
print('Using math.floor: ', math.floor(1.0 / 0.2))
Output:
Using //: 4.0
Using math.floor: …

John_335
- 21
- 5
2
votes
1 answer
How to compute trunc(a/b) with only the nearest-to-even rounding mode?
Given two IEEE-754 double-precision floating-point numbers a and b, I want to get the exact quotient a/b rounded to an integer towards zero.
A C99 program to do that could look like this:
#include
#include
#pragma STDC FENV_ACCESS…

Řrřola
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