How to use the argparse module to parse command line parameters in Python 2.x

There are many libraries and modules in Python that can help us parse command line parameters, among which argparse is a commonly used module. The argparse module provides a simple and flexible way to handle command line arguments, making it easy to write command line tools. This article explains how to use the argparse module in Python 2.x to parse command line arguments and provides some code examples.

1. Import argparse module
   First, we need to import the argparse module. In Python 2.x, the argparse module is located in the argparse package, so we need to use the import argparse statement to import the module.
2. Create an ArgumentParser object
   Next, we need to create an ArgumentParser object. The ArgumentParser object is one of the core objects in the argparse module and is responsible for parsing command line parameters.

parser = argparse.ArgumentParser()

3. Add command line parameters
   Add the command line parameters we need on the ArgumentParser object. We can use the add_argument() method to add command line parameters. This method accepts multiple parameters, including parameter names, parameter types, parameter abbreviations, etc.

parser.add_argument('input', help='输入文件名')
parser.add_argument('-o', '--output', help='输出文件名')
parser.add_argument('-v', '--verbose', action='store_true', help='详细输出')

The above code gives three examples:

• The first command line parameter input is a required parameter, which represents the input file name. We can access the value of this parameter through args.input.
• The second command line parameter output is an optional parameter, which represents the output file name. We can access the value of this parameter through args.output.
• The third command line parameter verbose is an optional parameter, which indicates whether to output detailed information. When the command line contains -v or --verbose, the value of args.verbose is True, otherwise it is False.

4. Parse command line parameters
   Call the parse_args() method of the ArgumentParser object to parse command line parameters.

args = parser.parse_args()

5. Using command line parameters
   After parsing the command line parameters, we can use them to perform the corresponding operations.

if args.output:
    # 输出文件名可用时，执行相应的操作
    print('输出文件名:', args.output)

if args.verbose:
    # 输出详细信息可用时，执行相应的操作
    print('详细输出')

In the above code, we use the if statement to check whether the command line parameters exist. Depending on whether the parameter is present or not, we can perform different operations.

6. Complete code example
   The following is a complete example of using the argparse module to parse command line parameters.

import argparse

parser = argparse.ArgumentParser()
parser.add_argument('input', help='输入文件名')
parser.add_argument('-o', '--output', help='输出文件名')
parser.add_argument('-v', '--verbose', action='store_true', help='详细输出')

args = parser.parse_args()

print('输入文件名:', args.input)

if args.output:
    print('输出文件名:', args.output)

if args.verbose:
    print('详细输出')

The above code will output corresponding information according to the status of the command line parameters. For example, executing the command python myscript.py input.txt -o output.txt -v will output the following results:

输入文件名: input.txt
输出文件名: output.txt
详细输出

By using the argparse module, we can write command line tools more conveniently , and provide users with a good command line interaction experience. I hope this article can help everyone understand and use the argparse module.

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