'and' operator in python3

Question

I'm pretty new to coding but I though I understood how the 'and' operator worked. In the example I provided I would have thought that the 'False' statement would get run not the 'True' statement. Can someone enlighten me on why this is not performing as I expected?

string = 'asdf'

if 'z' and 's' in string:
    True
else:
    False

Answer 1

The and keyword is part of an expression and it should be located between two subexpressions. Here you write 'z' and 's' in string which is interpreted as:

('z') and ('s' in string)

where the first subexpression, 'z' is more or less evaluated as True, while the second subexpression is a little more sophisticated (in your example, it is also intereted as True since 's' actually is in string.

Combining both subexpressions yields True (here).

You certainly wanted to write:

if 'z' in string and 's' in string: