Introduction to Python functions: Usage and examples of bool function

In Python, the bool function is a very useful built-in function. Its main function is to determine the Boolean value (True or False) of an object. The bool function is a very useful tool when we need to check the authenticity of an object.

bool function syntax:

bool([x])

Parameter x is optional. bool(x) will return True if x exists. bool(x) will return False if x does not exist or is False.

Let’s look at a few examples of bool functions:

Example 1: Check the authenticity of a numeric variable

x = 10
print(bool(x) ) # Return True

y = 0
print(bool(y)) # Return False

Example 2: Check the authenticity of string variables

s1 = "hello"
print(bool(s1)) # Return True

s2 = ""
print(bool(s2)) # Return False

Example 3: Check list True or false of type variable

lst = [1, 2, 3]
print(bool(lst)) # Return True

lst2 = []
print(bool( lst2)) # Return False

In the above example, we show examples of usage of bool function when checking the true and false of numbers, strings and list type variables. As you can see, in all examples, the bool function successfully detects the true or false value of the variable and returns the corresponding value.

In addition to checking the true and false of variables, there are some other common uses in Python, including:

1. Check whether the file exists: the bool function returns True to indicate the file Exists, returning False means the file does not exist.

import os.path
print(bool(os.path.exists("test.txt")))

2. Check whether the file size is 0: The bool function returns True to indicate that the file size is not 0, and returns False to indicate that the size is 0.

import os.path
print(bool(os.path.getsize("test.txt")))

3. Check whether the sequence is empty: the bool function returns True to indicate that the sequence is not empty, and returns False to indicate that the sequence is empty.

lst = [1, 2, 3]
if bool(lst):
    print("lst不为空")
else:
    print("lst为空")

In Python, the bool function has a wide range of applications and can be used to determine true and false in various scenarios. Whether it is in terms of variable types or file operations, the bool function is a very useful tool.

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