At the deepest level, computers operate exclusively using the numbers
1. This is what's known as binary code, and the ones and zeros are called bits, from “binary digit”.
The numbers from the decimal system that we know and love are encoded using binary numbers:
- 0 ← 0
- 1 ← 1
- 2 ← 10
- 3 ← 11
- 4 ← 100
- 5 ← 101
But does it deal with text? Computers don't know about letters, punctuation, or any other text characters. All these symbols are also encoded with numbers.
We can take the English alphabet and give each letter a number, starting with one:
- a ← 1
- b ← 2
- c ← 3
- d ← 4
- z ← 26
This is the essence of encoding.
When they're working, programs use encodings to convert numbers into characters and vice versa. And the program itself has no idea about the meaning of these characters.
These tables that match letters and numbers are called encodings. Besides letters of the alphabet, encoding tables include punctuation marks and other useful characters. You have probably encountered encodings such as ASCII and UTF-8.
Different encodings contain different numbers of characters. At first, small tables like ASCII were enough for programmers. But it has only Latin letters, a few simple characters like
? and special control characters like line feeds.
As computers spread further and further, countries needed their own comprehensive tables. This included Cyrillic letters, Chinese and Japanese characters, Arabic script, additional mathematical and typographic symbols, and later on emojis.
Today, it's usually [Unicode] variants that are used most often Unicode. It includes characters from almost all the written languages of the world.
In Python, you can query and display any ASCII character. The function
chr() is used for this. For example:
Symbol no. 63 - the question mark
?. You can print any character this way.
Use the ASCII code table. In this table, want to know about the decimal code (dec or decimal) with which the characters are encoded.
Using the example above and the table, display the following (each on its own line):
(Of course, you could be sneaky and cheat the tests by just doing
print('~') etc., but that would be no fun at all :)
The exercise doesn't pass checking. What to do? 😶
If you've reached a deadlock it's time to ask your question in the «Discussions». How ask a question correctly:
- Be sure to attach the test output, without it it's almost impossible to figure out what went wrong, even if you show your code. It's complicated for developers to execute code in their heads, but having a mistake before their eyes most probably will be helpful.
In my environment the code works, but not here 🤨
Tests are designed so that they test the solution in different ways and against different data. Often the solution works with one kind of input data but doesn't work with others. Check the «Tests» tab to figure this out, you can find hints at the error output.
My code is different from the teacher's one 🤔
It's fine. 🙆 One task in programming can be solved in many different ways. If your code passed all tests, it complies with the task conditions.
In some rare cases, the solution may be adjusted to the tests, but this can be seen immediately.
I've read the lessons but nothing is clear 🙄
It's hard to make educational materials that will suit everyone. We do our best but there is always something to improve. If you see a material that is not clear to you, describe the problem in “Discussions”. It will be great if you'll write unclear points in the question form. Usually, we need a few days for corrections.
By the way, you can participate in courses improvement. There is a link below to the lessons course code which you can edit right in your browser.
Encoding a set of characters encoded with numbers to represent text electronically.