For loop python multiple checks

Question

If I have strings like following:

my_string(0) = Your FUTURE looks good.
my_string(1) = your future doesn't look good.

I want to print both the lines with the following:

for stings in my_string:
   if 'FUTURE' or 'future' in string:
      print 'Success!'

my if loop works for the first condition with FUTURE, however, the second comparison with future doesn't work. What is the reason?

Answer 1

use:

if 'FUTURE' in string or 'future' in string:

or simply:

if 'future' in string.lower()

Why this failed:

if 'FUTURE' or 'future' in string:

is actually equivalent to :

True or ('future' in string)   # bool('FUTURE') --> True

as the first condition is always True so the next condition is never checked .In fact your if-condition is always True no matter what string contains.

A non-empty string is always True in python and or operation short-circuits as soon as a True value is found.

>>> strs1 = "your future doesn't look good."
>>> strs2 = "Your FUTURE looks good."
>>> 'FUTURE' or 'future' in strs1
'FUTURE'
>>> 'Foobar' or 'future' in strs1
'Foobar'
>>> 'Foobar' or 'cat' in strs1
'Foobar'
>>> '' or 'cat' in strs1    #  empty string is a falsey value,
False                       #  so now it checks the  next condition

Note that :

>>> 'FUTURE' in 'FOOFUTURE'
True

is True, as in operator looks for sub-strings not exact word match.

Use either regex or str.split to handle such cases.