Understanding Global and Local Variables in Python

This article discusses the usage scenarios of global and local variables in Python, helping readers understand when to use each type and providing example code for practical interface automation work.

Global variables are accessible throughout the entire program, while local variables are only accessible within the function or block where they are defined. They serve different purposes and offer distinct advantages in various scenarios.

Data sharing: Global variables allow different functions or code blocks to share data. When multiple functions need to access and modify the same data, global variables facilitate data sharing and transfer. Configuration information: Global variables can store program configuration details such as database connection information and API keys, making them easily accessible throughout the program.

base_url = "https://api.example.com"
access_token = None
def authenticate():
    global access_token
    # Call interface for authentication to obtain access token
    access_token = "abc123"
def make_request(endpoint):
    # Use global variable access_token for API request
    headers = {"Authorization": f"Bearer {access_token}"}
    response = requests.get(f"{base_url}/{endpoint}", headers=headers)
    # Process response data
authenticate()
make_request("users")

Local variables are used for temporary data within functions, effective only during function execution and not needed elsewhere. They also isolate variable namespaces between code blocks, preventing naming conflicts and variable pollution.

def calculate_area(radius):
    pi = 3.14159
    area = pi * radius ** 2
    print("圆的面积：", area)
calculate_area(5)

def calculate_sum(numbers):
    total = 0
    for num in numbers:
        total += num
    print("总和：", total)
calculate_sum([1, 2, 3, 4, 5])

def divide(a, b):
    try:
        result = a / b
        print("结果：", result)
    except ZeroDivisionError:
        print("除数不能为零")
divide(10, 2)

By appropriately using global and local variables, we can better organize and manage code, improving readability and maintainability. Choosing the suitable variable type based on specific needs and scenarios helps write efficient and understandable code.