python integer division error - modulo by zero - BUT divisor != 0

Question

I am new to doing simple math using python, so sorry if this is a silly question.

I have 8 variables that are all set to integers and these integers are used when performing a simple calculation.

a = 0
b = 17
c = 152
d = 1
e = 133
f = 19
g = 20
h = 0

answer = ( ( ( a / f ) + b + c ) - ( g + ( h / f ) ) ) / ( d / f )

print answer

When I run this code, I get the error, ZeroDivisionError: integer division or modulo by zero.

I have read about this error and all documentation points towards my divisor being zero, but if I print this with the numbers as strings in place of the variables, I get:

( ( ( 0 / 19 ) + 17 + 152 ) - ( 20 + ( 0 / 19 ) ) ) / ( 1 / 19 )

Nowhere in this statement is the divisor zero.

Please let me know how I need to change my expression in order to get the answer 2831. Note that I can change the type of the variables to a float or other. Thank you for your help!

Answer 1

Probably you are using Python 2.x, where x / y is an integer division.

So, in the below code: -

( 20 + ( 0 / 19 ) ) ) / ( 1 / 19 )

1 / 19 is an integer division, which results in 0. So the expression is essentially same as: -

( 20 + ( 0 / 19 ) ) ) / 0

Now you see where the error comes from.

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You can add following import in you python code, to enforce floating-point division: -

from __future__ import division

Or you could cast one of the integers to a float, using either float() or just by adding .0 to the initial value.