What is the purpose of parser.add_argument in Python?

The parser.add_argument is a method in the argparse module in Python used to add command-line arguments to the command-line parser.

By using parser.add_argument, you can define the parameters accepted by the command line and their attributes. These parameters can be either positional (without prefixes) or optional (with prefixes), and you can set the parameters’ types, default values, descriptions, etc.

The benefits of using parser.add_argument are as follows:

1. Standardizing the definition and parsing of command line parameters to make a program’s command line interface clearer and easier to use.
2. It can automatically validate the type and value validity of command line arguments.
3. Generate helpful information and usage tips to allow users to easily view available commands and parameter options when using command line tools.
4. Support command line auto-completion feature to enhance user’s command line interaction experience.

Here is a simple example that demonstrates how to use parser.add_argument to add command line arguments.

import argparse

# 创建命令行解析器
parser = argparse.ArgumentParser()

# 添加位置参数
parser.add_argument("name", help="输入你的名字")

# 添加可选参数
parser.add_argument("--age", type=int, default=18, help="输入你的年龄，默认为18岁")

# 解析命令行参数
args = parser.parse_args()

# 打印解析结果
print("你好，{}，你的年龄是{}岁".format(args.name, args.age))

In the above example, parser.add_argument is used to define two arguments: a positional argument called name and an optional argument called –age. The name argument is required, while the age argument is optional with a default value of 18. Afterwards, parser.parse_args() is used to parse the command-line arguments and store the results in the args object. Finally, the parsed results can be accessed through the args object for further actions.

For more information on how to use the argparse module, please refer to the official documentation at: https://docs.python.org/3/library/argparse.html.