>>> num1 = '2.0'

>>> print num1.isdigit()

False

>>> num2 = ''

>>> print num2.isdigit()

True

>>> num3 = '-3'

>>> print num3.isdigit()

False

>>> num4 = '3.0'

>>> print int(num4)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

ValueError: invalid literal for int() with base 10: '3.0'

>>> num5 = ''

>>> print int(num5)

3

>>> num6 = ''

>>> print float(num6)

3.0

>>> num6 = '-3'

>>> print int(num6)

-3

>>>