在特殊情况下，强制除法在Python中是浮点数

Question

This code prints 17, but I want the division to be performed using floating-point (so it should print 17.5 instead). How can I force the division to be in floating-point?

math = 8
physics = 9.5
algebra = 7.50
geometry = 10

**print "My GPA is %d" % ((math + physics + algebra + geometry)/2)**

Answer 1

%d is used for integers, for floats use %f . Using %d for floats will print only it's decimal part.

>>> print "My GPA is %f" % ((math + physics + algebra + geometry)/2)
My GPA is 17.500000

or:

>>> print "My GPA is %.1f" % ((math + physics + algebra + geometry)/2)
My GPA is 17.5

Using new style string formatting:

>>> print "My GPA is {:.1f}" .format((math + physics + algebra + geometry)/2)
My GPA is 17.5

Also note that integer division in py2.x truncates the output and returns an integer.

To fix that you should convert at least one of the operand to float.

>>> 3/2
1
>>> 3/float(2)
1.5
>>> 3/2.
1.5

or import python3.x's divison :

>>> from __future__ import division
>>> 3/2
1.5