21  comparisons boolean variables

In [1]: print( 5 > 2)
True

In [2]: print( 5 < 2)
False

In [3]: print( 2 == 2)
True

In [4]: print( "2" == 2)
False

In [5]: print( 1 != 2)
True

In [6]: print( 1 < "1")
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-eef05bdfaefd> in <module>
----> 1 print( 1 < "1")

TypeError: '<' not supported between instances of 'int' and 'str'

21.1 Question what is the result of following code execution? Why?

print("Bremen" > "bremen")

See Ascii table for answer to this question.

21.1.1 Logical operators and, or, not

  • and operator returns true if both sides are true
AND
True True True
True False False
False True False
False False False
  • or operator return trues if one of the sides are true
OR
True True True
True False True
False True True
False False False

  • not reverse the boolean,

    False -> True, True -> False



In [1]: birth_year = 1999

In [2]: birth_year < 2000 and birth_year < 2019
Out[2]: True

In [3]: birth_year < 1900 or birth_year > 1950
Out[3]: True

In [4]: not (birth_year < 1900 or birth_year > 1950 )
Out[4]: False