How to program Python for beginners?
How to program Python for beginners?
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Programming in Python for beginners
How does a Python program start?
I'm happy to respond in English for this question!
A Python program starts by executing the main function or entry point, which is specified at the top of the script file using the if __name__ == '__main__': block. This special block allows a Python program to be both reusable and executable.
Here's a step-by-step explanation of how a Python program starts:
File System: The first step is to locate the Python script on the file system. Typically, you would save your Python files with a.py extension. Python Interpreter: When you run the script using python filename.py, the operating system (e.g., Windows or macOS) launches the Python interpreter, which is responsible for executing the script. The Python interpreter is usually installed in the user's directory (e.g., C:Users<username>AppDataLocalProgramsPython on Windows). Line-by-Line Execution: When the Python interpreter starts executing a script, it begins reading and executing each line of code from top to bottom. Main Function or Entry Point: At the very beginning of any Python program is the if __name__ == '__main__': block, which serves as the main function or entry point. This block allows you to define a specific section of your code that should be executed when the script is run directly (e.g., python filename.py). Execution of Code: When the interpreter reaches the if __name__ == '__main__': block, it executes the code inside this block. This code usually contains the main logic and functionality of your program. Function Calls: As the Python program continues to execute, it might call other functions or modules defined elsewhere in the script or imported from external libraries. These function calls are executed when the interpreter reaches those lines of code. Termination: The Python program terminates when the if __name__ == '__main__': block has finished executing or when an error occurs that causes the program to crash.
In summary, a Python program starts by launching the Python interpreter, which then executes each line of code from top to bottom. The main function or entry point is defined using the if __name__ == '__main__': block, and this section of code contains the primary logic and functionality of your program.
