Bool()

Definition

bool() is a built-in Python function that converts a value to a Boolean, either True or False. It is commonly used in decision-making processes within code.

5 Must Know Facts For Your Next Test

1. bool() returns False for values like None, 0, empty sequences (e.g., '', [], {}), and returns True for all other values.
2. The bool() function can be used to check the truthiness of variables in conditional statements.
3. Using bool() on an object invokes the object's __bool__() method if it exists; otherwise, it calls __len__().
4. In Python, bool is a subclass of int where True equals 1 and False equals 0.
5. Common use cases include validating inputs and controlling the flow of loops and conditionals.

Review Questions

• What does bool(None) return?
• How does bool() determine if custom objects should be considered True or False?
• Is there any difference between using bool(1) and just writing True?

Related terms

Boolean: A data type with two possible values: True or False.

__bool__(): A special method used to define the truthiness of an object when passed to bool().

__len__(): A special method that returns the length of an object; used by bool() if __bool__() isn't defined.