Converting a String to a Boolean in Python [duplicate]

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 · 2021-02-02 12:11:44Z

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 2, 2021 at 12:11

answered Feb 24, 2014 at 19:59

jonrsharpe

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2 Comments

softghost Over a year ago

Thank you, jonrsharpe :)

leumas95 Over a year ago

This works but I thought someone should mention the issues with eval: stackoverflow.com/questions/1832940/…

CLeo-Dev · Accepted Answer · 2017-08-08 09:16:34Z

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 8, 2017 at 9:16

CLeo-Dev

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answered Feb 24, 2014 at 20:13

sabbahillel

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