boolean-expression - w3toppers.com

What is “!!” in C? [duplicate]

! is negation. So !! is negation of negation. What is important is the fact that the result will be an int. !!x if x == 0 is !!0, that is !1, that is 0. !!x if x != 0 is !!(!0), that is !!1, that is !0, that is 1. !! is used commonly … Read more

Python `if x is not None` or `if not x is None`? [closed]

There’s no performance difference, as they compile to the same bytecode: >>> import dis >>> dis.dis(“not x is None”) 1 0 LOAD_NAME 0 (x) 2 LOAD_CONST 0 (None) 4 COMPARE_OP 9 (is not) 6 RETURN_VALUE >>> dis.dis(“x is not None”) 1 0 LOAD_NAME 0 (x) 2 LOAD_CONST 0 (None) 4 COMPARE_OP 9 (is not) 6 … Read more

Priority of the logical operators NOT, AND, OR in Python

It’s NOT, AND, OR, from highest to lowest according to the documentation on Operator precedence Here is the complete precedence table, lowest precedence to highest. A row has the same precedence and chains from left to right 0. := 1. lambda 2. if – else 3. or 4. and 5. not x 6. in, not … Read more

‘and’ (boolean) vs ‘&’ (bitwise) – Why difference in behavior with lists vs numpy arrays?

and tests whether both expressions are logically True while & (when used with True/False values) tests if both are True. In Python, empty built-in objects are typically treated as logically False while non-empty built-ins are logically True. This facilitates the common use case where you want to do something if a list is empty and … Read more

What is Truthy and Falsy? How is it different from True and False?

All values are considered “truthy” except for the following, which are “falsy”: None False Zeros, including: 0 0.0 0j decimal.Decimal(0) fraction.Fraction(0, 1) Empty sequences and collections, including: [] – an empty list {} – an empty dict () – an empty tuple ” – an empty str b” – an empty bytes set() – an … Read more

Why does “a == x or y or z” always evaluate to True?

In many cases, Python looks and behaves like natural English, but this is one case where that abstraction fails. People can use context clues to determine that “Jon” and “Inbar” are objects joined to the verb “equals”, but the Python interpreter is more literal minded. if name == “Kevin” or “Jon” or “Inbar”: is logically … Read more