Using Python’s Command Line Arguments: A Simple Guide

Guidelines for the use of Python command line parameters

[Introduction]
In the process of developing and using Python programs, it is often necessary to obtain user input from the command line parameters. Python provides a wealth of libraries and methods to handle command line parameters. This article will introduce some common methods and techniques to help developers better use command line parameters.

[Basic Concept]
Command line parameters are the parameters required when the program is run on the command line. It can help the program achieve different operations and functions. In Python, you can use the sys module and the argparse module to parse and process command line arguments.

[sys module]
The sys module is a built-in module of Python that provides functions closely related to the Python interpreter. It also contains methods for handling command line arguments. The following are several commonly used methods in the sys module:

1. sys.argv: Returns a list containing command line parameters. The first element of the list is the name of the program, and the following elements are the parameters entered by the user. Specific parameters can be obtained through sys.argv[index]. For example:

import sys

# 获取用户输入的参数
for i in range(len(sys.argv)):
    print("参数", i, "：", sys.argv[i])

2. sys.stdin: used to read data input from the command line. You can use the sys.stdin.read() method to obtain the entire input content, or use the sys.stdin.readline() method to read the input content line by line. For example:

import sys

# 逐行读取输入内容
for line in sys.stdin:
    print("读取到的内容：", line)

[argparse module]
The argparse module is a module in the Python standard library used to process command line parameters. It provides more advanced functions, can handle complex command line parameters, and can also generate help information. The following is the basic usage of the argparse module:

import argparse

# 创建ArgumentParser对象
parser = argparse.ArgumentParser(description='命令行参数使用示例')

# 添加参数
parser.add_argument('-a', '--arg1', type=int, help='参数1')
parser.add_argument('-b', '--arg2', type=str, help='参数2')

# 解析命令行参数
args = parser.parse_args()

# 输出参数值
print("参数1的值：", args.arg1)
print("参数2的值：", args.arg2)

In the above code, we create an ArgumentParser object and add two parameters using the add_argument() method. Among them, '-a' and '--arg1' represent the short name and long name of the parameter, type specifies the type of the parameter, and help is used to generate help information. When parsing command line parameters and obtaining parameter values, they can be obtained through args.arg1.

[Summary]
This article introduces the basic methods and common techniques for processing command line parameters in Python. The sys module can be used to simply obtain and process command line parameters, while the argparse module provides more flexible and advanced functions that can handle complex command line parameters and generate help information. Based on actual needs, developers can choose an appropriate method to handle command line parameters to improve the flexibility and ease of use of the program.

[Appendix]
Official documentation of the sys module: https://docs.python.org/3/library/sys.html
Official documentation of the argparse module: https://docs. python.org/3/library/argparse.html

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