What is Argparse?

Argparse is a module that comes pre-installed when you install Python. It allows for the creation of user-friendly command-line interfaces.

Creating a CLI Program to Find the Area of a Rectangle

To start using argparse to recreate the example above, you will need to import the pacakge:

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# the following code will be contained within a file called area.py

import argparse

Now we will create a simple method to multiply and return two numbers, like so:

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def area_of_rectangle(length, width):

    return length * width

This method will be called when the program is executed. The parameters length and width will be extracted from the command line arguments.

Now we must create a parser to handle the parsing of command-line arguments along with two positional arguments that we want to extract, i.e. the length and the width of the rectangle.

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parser = argparse.ArgumentParser(description='Calculates the area of a rectangle')



parser.add_argument('length', default=0, type=int, help='An integer for the length of the rectangle')

parser.add_argument('width', default=0, type=int, help='An integer for the width of the rectangle')

We can use the values of these arguments by calling upon parser.parse_args().

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args = parser.parse_args()

area = area_of_rectangle(args.length, args.width)

print('The area of your rectangle is: ', area, ' units squared.')

Putting everything together should look like this:

# area.py

import argparse



def area_of_rectangle(length, width):

    return length * width



parser = argparse.ArgumentParser(description='Calculates the area of a rectangle')



parser.add_argument('length', default=0, type=int, help='An integer for the length of the rectangle')

parser.add_argument('width', default=0, type=int, help='An integer for the width of the rectangle')



args = parser.parse_args()

area = area_of_rectangle(args.length, args.width)

print('The area of your rectangle is: ', area, ' units squared.')

Thats about it! Argparse will now parse your command-line agruments for integers to be used in our method. Every parser will have a -h optional argument by default; this option will display the help message along with the parser’s description.