# Logical operators

The **logical operators** in Python are used to combine the **true** or** false** values of variables (or expressions) so you can figure out their resultant truth value. Three logical operators are available in Python:

**1. and** – returns **True** only if both operands are true. In any other case,** False** will be returned. For example, the following expression will evaluate to True: **5 < 7 and 5 > 3**, because 5 is indeed less than 7 and greater than 3. Here is the **and operator’s truth table** (a table that lists all the possible inputs and the results for the logical operators):

First operand | Second operand | Result |
---|---|---|

True | True | True |

True | False | False |

False | True | False |

False | False | False |

Here are a couple of examples:

>>> 5 < 7 and 5 > 3 True >>> >>> 3 > 3 and 55 > 30 False >>> 15 / 3 >= 200 and 3 == 3 False >>> 55 == 55 and 3 <= 3 True

**2. or** – returns **True** when one or both of the operands are true. For example, the expression **5 < 3 or 3 == 3** will return **True** because the second operand (**3 == 3**) evaluates to **True**. Only if both operands are false will **False** be returned. The truth table for this operator looks like this:

First operand | Second operand | Result |
---|---|---|

True | True | True |

True | False | True |

False | True | True |

False | False | False |

Examples:

>>> 3 == 3 or 5 < 3 True >>> 15 < 3 or 5 > 3 True >>> 12 <= 1 or 5 < 1 False >>> 20 + 3 >= 23 or 5 != 5 True

**3. not** – negates the truth value of a single operand. In other words, **True** becomes** False** and vice versa. The truth table here is smaller because only a single operand is used:

Operand | Result | |
---|---|---|

True | False | |

False | True |

Examples:

>>> not True False >>> not False True >>> not 5 > 3 False >>> not (5 > 3 and 5 > 2) False >>> not (5 > 3 and 5 < 33) False >>> not (5 < 3 and 5 < 33) True

Let’s expain the last example – **not (5 < 3 and 5 < 33) **–** **and why it returns **True**. Simply evaluate the expression in the parentheses first:

**5 < 3** – 5 isn’t smaller than 3, so this expression is **false**.

**5 < 33** – 5 is smaller than 33, so this expression is **true**.

From the truth table for the **and** operator above, we know that** False** and **True** return **False**. So the expression **5 < 3 and 5 < 33** will return **False**. Now, we just need to apply the **not** operator, so **False** becomes **True**.