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Boolean logic: AND, OR, NOT
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Boolean logic works with only two values: True and False (or 1 and 0). It is how programs and circuits make decisions.
Three operators
AND is True only if both inputs are True.
OR is True if at least one input is True.
NOT flips the input: NOT True = False.
They are named after George Boole, a 19th-century mathematician.
OR is True if at least one input is True.
NOT flips the input: NOT True = False.
They are named after George Boole, a 19th-century mathematician.
Truth tables
A truth table shows the output for every possible input. 1 = True, 0 = False.
Boolean logic in Python
Python uses and, or and not.
age = 12
print(age > 10 and age < 13)
prints True, because both parts are True.
A cinema rule: allowed in if (age >= 12) or (with_adult == True).
age = 12
print(age > 10 and age < 13)
prints True, because both parts are True.
A cinema rule: allowed in if (age >= 12) or (with_adult == True).
A = 1, B = 0. Work out NOT (A AND B).
- A AND B = 1 AND 0 = 0.
- NOT 0 = 1.
Answer: 1
AND needs both inputs true, OR needs at least one, NOT flips the value. A truth table lists the output for every combination of inputs.
The interactive lesson includes the diagrams for this topic.
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