Python bool Function with Examples

Python is a powerful programming language that provides numerous built-in functions to simplify the coding process. One such function is the bool() function, which is used to convert a given value to a Boolean value, i.e., either True or False.
In this blog post, we will explore the Python bool() function, its syntax, arguments, return value, and examples to understand how to use it in your code.

Syntax and Arguments:

The syntax of the bool() function in Python is straightforward. It takes only one argument and returns either True or False. Here is the syntax:

bool([value])

The bool() function takes only one argument. The argument can be any data type, such as a string, integer, list, tuple, or dictionary. The function returns True if the value of the argument is true, and False if the value of the argument is false.

Return Value: The bool() function returns either True or False, depending on the value of the argument. If the argument is considered true, the function returns True. Otherwise, it returns False.
Here are the rules for determining if an argument is considered true:

• Numeric types (int, float, complex) are considered true if they are not zero.
• Non-empty sequences (list, tuple, string) are considered true.
• Non-empty dictionaries are considered true.
• Non-empty sets are considered true.
• All other values are considered true.

Examples:

Here are five unique examples that demonstrate the use of the bool() function.

Example 1: bool() function with integer value

print(bool(0))
print(bool(42))

Output:
False
True

In this example, we have passed two integer values to the bool() function. The first value is 0, which is considered false. Therefore, the function returns False. The second value is 42, which is considered true. Therefore, the function returns True.

Example 2: bool() function with string value

print(bool(""))
print(bool("Hello"))

Output:
False
True

In this example, we have passed two string values to the bool() function. The first value is an empty string, which is considered false. Therefore, the function returns False. The second value is a non-empty string, which is considered true. Therefore, the function returns True.

Example 3: bool() function with list value

print(bool([]))
print(bool([1, 2, 3]))

Output:
False
True
In this example, we have passed two list values to the bool() function. The first value is an empty list, which is considered false. Therefore, the function returns False. The second value is a non-empty list, which is considered true. Therefore, the function returns True.

Example 4: bool() function with dictionary value

print(bool({}))
print(bool({"name": "John", "age": 30}))

Output:
False
True

In this example, we have passed two dictionary values to the bool() function. The first value is an empty dictionary, which is considered false. Therefore, the function returns False. The second value is a non-empty dictionary, which is considered true. Therefore, the function returns True.

Example 5: bool() function with user-defined function

Yes, you can use the bool() function with user-defined functions in Python. Let’s take a look at an example.

Suppose we have a function called is_even() that takes a number as input and returns True if the number is even and False if it is odd. We can use the bool() function to convert the output of this function to a Boolean value.

def is_even(num):
    if num % 2 == 0:
        return True
    else:
        return False

num = 4

is_num_even = bool(is_even(num))
print(is_num_even)

Output:
True

In the above code, we define a function called is_even() that takes a number as input and returns True if the number is even and False if it is odd. We then call this function with the number 4 and store the output in a variable called is_num_even. We then use the bool() function to convert the output of the is_even() function to a Boolean value and print it to the console.

When to use Python bool() function:

The bool() function can be used in a variety of situations where you need to evaluate a value as True or False. We can use it to check if a value is true or false, and to perform conditional statements. We can also use it to check if a variable has a value or not. The bool() function is commonly used in programming to evaluate conditions and make decisions based on the results.

1. Conditional statements: Conditional statements such as if, elif, and while statements rely on Boolean values to make decisions. You can use the bool() function to convert a given value to a Boolean value and use it in these statements.

   x = 10
   if bool(x):
     print("x is true")
   else:
     print("x is false")
   

   Output: x is true

2. Filtering data: You can use the bool() function to filter data by selecting only the true values. For example, if you have a list of numbers and you want to select only the even numbers, you can use the bool() function to filter out the odd numbers.

   numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
   even_numbers = [num for num in numbers if bool(num % 2 == 0)]
   print(even_numbers)
   

   Output: [2, 4, 6, 8, 10]

3. Data validation: When working with user input, you may need to validate the data to ensure that it is in the correct format. You can use the bool() function to check if the input is valid or not. For example, if you have a form that requires the user to enter a valid email address, you can use the bool() function to check if the email address is valid.

   email = "example@example.com"
   if bool('@' in email and '.' in email):
     print("Valid email")
   else:
     print("Invalid email")
   

   Output: Valid email

4. Checking if a variable is defined: Sometimes, you may need to check if a variable is defined before using it in your code. You can use the bool() function to check if the variable exists and is not None.

   x = None
   if bool(x):
     print("x is defined")
   else:
     print("x is not defined")
   

   Output: x is not defined

Conclusion:

The bool() function in Python is a powerful tool that can help us evaluate conditions and make decisions in our programs. It takes only one argument and returns either True or False, depending on the value of the argument. We can use it to check if a value is true or false, and to perform conditional statements.

List Of All Python Built-in Functions:

Click on the following link to view the complete list of built-in functions.

Python Built-in Functions