Python int float rounding

Question

While playing with python, I came across this:

a = 1/(2.2 - 2)

print a       #prints out 5.0
print int(a)  #prints out 4

I suspect the pro

Answer 1

You are quite right in your suspicion. The root cause is that 2.2 cannot be represented exactly as a float:

In [38]: '%.20f' % 2.2
Out[38]: '2.20000000000000017764'

The rest follows from this:

In [45]: '%.20f' % (2.2 - 2)
Out[45]: '0.20000000000000017764'

In [46]: '%.20f' % (1 / (2.2 - 2))
Out[46]: '4.99999999999999555911'