Why Does `(1 in [1,0] == True)` Evaluate to False in Python?

Unraveled: The Mystery of Why '(1 in [1,0] == True)' Evaluates to False

The expression '(1 in [1,0] == True)' in Python might initially seem counterintuitive, evaluating to False when one might expect it to be True. To unravel this mystery, we must delve into the inner workings of Python's evaluation process.

Curiously, Python interprets this expression as a chain of comparisons rather than a straightforward check against a boolean value. The true structure of the expression is revealed as:

(1 in [1,0]) and ([1,0] == True)

This chain of comparisons evaluates to False because the first expression, '(1 in [1,0])', returns True, and the second expression, '([1,0] == True)', evaluates to False.

This phenomenon of comparison chaining also occurs in other expressions, such as 'a < b < c', which translates to:

(a < b) and (b < c)

without redundant evaluation of 'b' twice.

It is crucial to understand this aspect of Python's evaluation behavior to avoid unexpected results when dealing with complex expressions involving comparisons.

The above is the detailed content of Why Does `(1 in [1,0] == True)` Evaluate to False in Python?. For more information, please follow other related articles on the PHP Chinese website!