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Challenge 92: Extension Extractor

curriculum/challenges/english/blocks/daily-coding-challenges-python/68f6587287ad1f4ad39b0c7e.md

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--description--

Given a string representing a filename, return the extension of the file.

  • The extension is the part of the filename that comes after the last period (.).
  • If the filename does not contain a period or ends with a period, return "none".
  • The extension should be returned as-is, preserving case.

--hints--

get_extension("document.txt") should return "txt".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension("document.txt"), "txt")`)
}})

get_extension("README") should return "none".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension("README"), "none")`)
}})

get_extension("image.PNG") should return "PNG".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension("image.PNG"), "PNG")`)
}})

get_extension(".gitignore") should return "gitignore".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension(".gitignore"), "gitignore")`)
}})

get_extension("archive.tar.gz") should return "gz".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension("archive.tar.gz"), "gz")`)
}})

get_extension("final.draft.") should return "none".

js
({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(get_extension("final.draft."), "none")`)
}})

--seed--

--seed-contents--

py
def get_extension(filename):

    return filename

--solutions--

py
def get_extension(filename):
    last_dot = filename.rfind('.')
    
    if last_dot == -1 or last_dot == len(filename) - 1:
        return "none"
    
    return filename[last_dot + 1:]