Logic
Python allows us to control the flow of our program using logical operators and truth values: True and False.
Operators
Python also allows us to compare attributes of data by using the following:
- Equality (==)
- Greater than or equal (>=)
- Less than or equal (<=)
- Less than (<)
- Greater than (>)
- Not equal (!=)
Double equals is used for checking equality and not used for variable assignment
Here are some examples:
name = "John"
age = 27
name == "James" # equals False
age >= 18 # equals True
22 != '22' # equals True
The last example shows that the both the equality and the not-equality operator checks for types as well. A string will never be ‘equal’ to a number.
Truth Table
There are 2 operators that allow for the combination of these truth values: and and or
These operators will follow the following set of logical rules:
| Statement 1 | Statement 2 | Statement 1 and Statement 2 | Statement 1 or Statement 2 |
|---|---|---|---|
| T | T | T | T |
| T | F | F | T |
| F | T | F | T |
| F | F | F | F |
Logical statements have a similar execution style to that of Math.
- Parentheses are computed first.
- Proceeds from left to right.
(True and False) or True # equals True