Converting a String to a Boolean in Python

Question

How to convert a String to a Boolean? For example:

str = "False and False or True and True"
str = "( "+str+" )"
str = str.replace("and",") and (")

returns

str == '( False ) and ( False or True ) and ( True )'

How to execute str for result 'False'?

jonrsharpe · Accepted Answer · 2021-02-02T12:11:44.240

5

I think you are looking for eval:

>>> eval('( False ) and ( False or True ) and ( True )')
False

Notes:

don't use eval on user input, see e.g. Why is using 'eval' a bad practice? and
don't use str as a variable name; it shadows a Python built-in.

edited Feb 02 '21 at 12:11

answered Feb 24 '14 at 19:59

jonrsharpe

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Thank you, jonrsharpe :) – softghost Feb 24 '14 at 20:02
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This works but I thought someone should mention the issues with eval: https://stackoverflow.com/questions/1832940/why-is-using-eval-a-bad-practice – leumas95 Nov 14 '17 at 20:59

score 2 · Answer 2 · edited Aug 08 '17 at 09:16

2

You can use a function that tranlates appropriate strings to True and False

def str2bool(self, v): # Note the self to allow it to be in a class
  return v.lower() in ('yes', 'true', 't', '1', 'yea', 'verily')  # lower() is a method

This will allow you to analyze various user inputs as well.

edited Aug 08 '17 at 09:16

CunivL

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answered Feb 24 '14 at 20:13

sabbahillel

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Converting a String to a Boolean in Python

2 Answers2