Reveal the Number

Reveal the Number


You are given a string of different characters (letters, digits and other symbols). The goal is to "extract" the number from the string: concatenate only digits, number sign and "." (if present) and return the result in number format. If no number can be extracted (no digits in the given string) - return None. Read preconditions below for some additional rules.

Expected behavior:

  • take into consideration the LAST number sign before the FIRST digit;
  • take into consideration the FIRST dot in the string (It's guaranteed, that it goes after at least one digit or has at least one digit after). If there is a dot, return as float, otherwise - integer.

Input: String (str).

Output: Integer (int), float (float) or None.


assert reveal_num("F0(t}") == 0
assert reveal_num("Utc&g") == None
assert reveal_num("-aB%|_-+2ADS.12+3.ADS1.2") == 2.12312
assert reveal_num("-aB%|_+-2ADS.12+3.ADS1.2") == -2.12312
Invalid hot key. Each hot key should be unique and valid
Hot keys:
CheckiO Extensions

CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.

In order to install CheckiO client you'll need installed Python (version at least 3.8)

Install CheckiO Client first:

pip3 install checkio_client

Configure your tool

checkio --domain=py config --key=

Sync solutions into your local folder

checkio sync

(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)

checkio serv -d

Alternatevly, you can install Chrome extension or FF addon

checkio install-plugin
checkio install-plugin --ff
checkio install-plugin --chromium

Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.

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