The usage of main in Python.

In Python, the main function is a special function used to specify the entry point of a program. When the Python interpreter runs a script file, it starts executing from the main function of the program.

The main function is typically placed at the end of a script and is used with “if __name__ == ‘__main__'” to determine if it should be executed. This is because in Python, a script can be run as a standalone program or imported as a module and used by other programs.

Here is a simple example:

def main():
    # 主程序逻辑
    print("Hello, World!")

if __name__ == '__main__':
    main()

In this example, the main function prints “Hello, World!”. When the script is run directly, the condition if __name__ == ‘__main__’: is true, and the main function is called and executed. If the script is imported as a module by another program, the condition if __name__ == ‘__main__’: is false, and the main function is not executed.

By using the main function, we can encapsulate the logic of the program in a function, making the code more modular and reusable. Additionally, it provides a convenient way to test and debug the program.