File Extensions

Even though Windows and macOS sometimes hide them, most files have file extensions, a suffix that starts with a period (.) at the end of their name. For instance, file names for GIFs end with .gif, and file names for JPEGs end with .jpg or .jpeg. When you double-click on a file to open it, your computer uses its file extension to determine which program to launch.

Web browsers, by contrast, rely on media types, formerly known as MIME types, to determine how to display files that live on the web. When you download a file from a web server, that server sends an HTTP header, along with the file itself, indicating the file’s media type. For instance, the media type for a GIF is image/gif, and the media type for a JPEG is image/jpeg. To determine the media type for a file, a web server typically looks at the file’s extension, mapping one to the other.

See MIME types for common types.

In a file called extensions.py, implement a program that prompts the user for the name of a file and then outputs that file’s media type if the file’s name ends, case-insensitively, in any of these suffixes:

.gif .jpg .jpeg .png .pdf .txt .zip 

If the file’s name ends with some other suffix or has no suffix at all, output application/octet-stream instead, which is a common default.

Hints

• Recall that a str comes with quite a few methods, per string-methods.

Before You Begin

From the root of your repository execute cd conditionals So your current working directory is ...

/conditionals $:

Next execute

code extensions.py

to make a file called extensions.py where you’ll write your program.

Success

Your program must have a function called extension that takes a string argument and returns a string representing the media type. Your main function must call this extension function with the user’s input and print the result.

How to Test

Here’s how to test your code manually:

Run your program with python extensions.py. Type happy.jpg and press Enter. Your program should output:

image/jpeg

Run your program with python extensions.py. Type document.pdf and press Enter. Your program should output:

application/pdf

Be sure to test each of the other file formats, vary the casing of your input, and “accidentally” add spaces on either side of your input before pressing enter. Your program should behave as expected, case- and space-insensitively.

Pytest

You can execute the below to check your code using pytest from the root directory.

pytest .\tests\conditionals\test_extensions.py

A green output from running the test means it was successful. A red output means there is a bug in your code that you need to fix.

How to Submit

From github desktop or the command line, commit your changes and push them to your repository.

Codespaces

If you are using codespaces, you can commit your changes directly from the Codespace interface. Click on the Source Control icon in the left sidebar, then click on the "..." button and select "Commit to main". Enter a commit message and click "Commit".

Codespace terminal or your local terminal.

Note

You will need to have installed git-scm for this to work locally

At the /datatypes $ prompt in your terminal:

git add -A 

Add all changed files in the repository to be committed

git commit -m "your message here"

Commit all changes in the REPO with the comment “your message here“ note: If the file is not complete, adjust the comment to describes what is being committed

Note

Remember to replace "your message here" with a meaningful commit message that describes your changes.

git push 

Push all changes to the repo.