Python And Or statements acting ..weird

Question

I have this simple line of code:

i = \" \"

if i != \"\" or i != \" \":
    print(\"Something\")

This should be simple, if i is not empty <

Answer 1

De Morgan's laws,

"not (A and B)" is the same as "(not A) or (not B)"

also,

"not (A or B)" is the same as "(not A) and (not B)".

In your case, as per the first statement, you have effectively written

if not (i == "" and i == " "):

which is not possible to occur. So whatever may be the input, (i == "" and i == " ") will always return False and negating it will give True always.

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Instead, you should have written it like this

if i != "" and i != " ":

or as per the quoted second statement from the De Morgan's law,

if not (i == "" or i == " "):