Logical Expressions: and, or, not

In Python, comparison operations (==, !=, <, >, <=, >=) produce a logical value: True or False. For example, 5 > 3 is True and 5 == 3 is False. Such values belong to the bool type and are used as conditions in if and while statements.

Three logical operations let us combine several conditions. and gives True only if both conditions are true, or gives True if at least one is true, and not reverses a value. For example, x > 0 and x < 10 checks that x lies between 0 and 10.

Operations are carried out in a fixed order: comparison first, then not, then and, and finally or. To change the order or make the code clearer, use parentheses: (a > 0 or b > 0) and c > 0. Python also allows chained comparison: 0 < x < 10 means the same as 0 < x and x < 10.

Example: let us check a user’s age. age = int(input("Yoshingiz: ")), then if age >= 7 and age <= 17: we print print("Siz maktab o‘quvchisi bo‘lishingiz mumkin"), otherwise the else branch runs. The most common mistake in logical expressions is mixing up = (assignment) and == (comparison).

Key takeaways

• The result of a comparison is a bool value: True or False.
• and means both are true, or means at least one is true, not means the opposite.
• Order of operations: comparison, not, and, or; parentheses change the order.
• = assigns a value, while == compares.