How to use the argparse module to parse command line parameters in Python 3.x

How to use the argparse module in Python 3.x to parse command line parameters

Introduction:
In actual software development, it is often necessary to pass parameters through the command line, which is especially important for large projects . Python provides the argparse module, which provides a clear and concise way to parse command line arguments. This article will introduce the basic usage of the argparse module and illustrate it with code examples.

1. Basic concepts of argparse module
argparse is part of the Python standard library and is used to parse command line parameters. It provides a way to easily define command line parameters and options while automatically generating help information. The argparse module has the following two main classes and some commonly used functions:

1. ArgumentParser class: used to create parser objects and set rules for command line parameters and options.
2. ArgumentGroup class: used to group parameters to make the help information clearer.

Commonly used functions are:

• add_argument(): used to add command line parameters and options.
• parse_args(): Used to parse command line parameters and return a namespace object containing parameter information.

2. Steps to use the argparse module
The steps to use the argparse module to parse command line parameters are as follows:

1. Create an ArgumentParser object.
2. Use the add_argument() method to add command line arguments and options.
3. Use the parse_args() method to parse command line arguments.
4. According to the parsing results, complete the corresponding operations.

The following is a code example:

import argparse

# Step 1: 创建 ArgumentParser 对象
parser = argparse.ArgumentParser(description='命令行参数解析示例')

# Step 2: 添加命令行参数和选项
parser.add_argument('name', help='姓名')
parser.add_argument('--age', dest='age', type=int, default=18, help='年龄')
parser.add_argument('--gender', choices=['male', 'female'], help='性别')

# Step 3: 解析命令行参数
args = parser.parse_args()

# Step 4: 根据解析结果，完成相应操作
print('姓名：', args.name)
print('年龄：', args.age)
print('性别：', args.gender)

In the above code, we first create a parser object through the argparse.ArgumentParser classparser and specify a short description.

Next, we used the add_argument() method to add name, --age and --genderThese three parameters and related options. Among them, name is a required positional parameter with no default value; --age is an optional long option, type is integer, and the default value is 18; - -gender is an optional long option that can only be selected from the two options male and female.

Finally, we use the parse_args() method to parse the command line arguments and save the parsing results in the args namespace object. The values ​​of these parameters and options can be accessed directly through.

3. Running results
We can run the above code by passing parameters through the command line. For example:

$ python3 argparse_demo.py Tom --age 20 --gender male
姓名： Tom
年龄： 20
性别： male

4. Summary
The argparse module provides a simple and flexible way to parse command line parameters. By using argparse, we can easily define and use command line parameters and options, and generate clear help information. It is an important tool for processing command line parameters in Python and is worth mastering and using by developers.

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