Why does Python return 0 for simple division calculation?
Question:
Why does this simple calculation return 0
>>> 25/100*50
0
while this actually calculates correctly?
>>> .25*50
12.5
>>> 10/2*2
10
What is wrong with the first example?
Answers:
In Python 2, 25/100 is zero when performing an integer divison. since the result is less than 1.
You can “fix” this by adding from __future__ import division to your script. This will always perform a float division when using the / operator and use // for integer division.
Another option would be making at least one of the operands a float, e.g. 25.0/100.
In Python 3, 25/100 is always 0.25.
25/100 is an integer calculation which rounds (by truncation) to 0.
This is a problem of integer truncation (i.e., any fractional parts of a number are discarded). So:
25 / 100 gives 0
However, as long as at least one of the operands in the division is a float, you’ll get a float result:
25 / 100.0 or 25.0 / 100 or 25.0 / 100.0 all give 0.25
-
In Python 2: 25/100 is an integer division by default
-
In Python 3: 25/100 is always 0.25.
I solved this problem just by doing this trick.
(25 * 1.0) / 100 * 50
So, (1.0) makes sure that the numerator be float type
Python 2 returns zero for integer division if result is less than 1.
Solution is to convert one of the integers to float e.g.
float(25)/100*50
Why does this simple calculation return 0
>>> 25/100*50
0
while this actually calculates correctly?
>>> .25*50
12.5
>>> 10/2*2
10
What is wrong with the first example?
In Python 2, 25/100 is zero when performing an integer divison. since the result is less than 1.
You can “fix” this by adding from __future__ import division to your script. This will always perform a float division when using the / operator and use // for integer division.
Another option would be making at least one of the operands a float, e.g. 25.0/100.
In Python 3, 25/100 is always 0.25.
25/100 is an integer calculation which rounds (by truncation) to 0.
This is a problem of integer truncation (i.e., any fractional parts of a number are discarded). So:
25 / 100 gives 0
However, as long as at least one of the operands in the division is a float, you’ll get a float result:
25 / 100.0 or 25.0 / 100 or 25.0 / 100.0 all give 0.25
-
In Python 2: 25/100 is an integer division by default
-
In Python 3: 25/100 is always 0.25.
I solved this problem just by doing this trick.
(25 * 1.0) / 100 * 50
So, (1.0) makes sure that the numerator be float type
Python 2 returns zero for integer division if result is less than 1.
Solution is to convert one of the integers to float e.g.
float(25)/100*50