Boolean is a datatype named after George Boole (1815-1864). A Boolean variable can take only two values, True or False. The main use of this type is in logical expressions. Here are some examples:
a = True b = 30 > 45 # b gets the value False
Boolean expressions are often used in conjunction with the if statement:
if x > 0:
print("positive")
else:
print("nonpositive)Boolean operations are performed using the and, or, and not keywords in Python:
True and False # False False or True # True (30 > 45) or (27 < 30) # True not True # False not (3 > 4) # True
The operators follow some precedence rules (refer to section Executing scripts in Chapter 1, Getting started) which would make the parentheses in the third line and in the last obsolete (it is a good practice to use them anyway to increase the readability of your code). Note that the and operator is implicitly chained in the following Boolean expressions:
a...
