Last night was the final night of the Intro to Python Coding course that I’ve been teaching on behalf of Computer Coach for the past five weeks — Mondays and Wednesdays, 6:00 p.m. to 10:00 p.m..
I’d like to congratulate the students! It’s not easy to spend four hours an evening twice a week learning something completely new and unknown to you, but the students did just that. If you’ve ever been in any of my Tampa iOS Meetup sessions, you’ve seen my teaching technique — you’re not passively watching slides, but coding along with me, and even experimenting, just to see what happens. That’s I what I did with the Python class — we entered code and saw what happened, hopefully learning along the way.
As a farewell present to the students, I sent them a copy of So You Want to be a Wizard, a little “zine” written by Julia “b0rk” Evans for programmers who are starting out that’s full of good advice. I hope it helps them through those moments that every programmer has, when nothing seems to work and all you want to do is throw your computer out the window. I’ve posted it here as well, partly because it’s full of good advice that even experts need to remember, and partly because I want to make sure that everyone knows about Julia’s works.
Even the table of contents lets you that that you’re in for a fun read:
Julia has a whole set of zines, some of which are free…
…and some fancier ones, which come at a reasonable price, even for groups:
Once again, congratulations to the Intro to Python Coding students!
For the benefit of my classmates in the UC Baseline program (see this earlier post to find out what it’s about), I’m posting a regular series of notes here on Global Nerdy to supplement the class material. As our instructor Tremere said, what’s covered in the class merely scratches the surface, and that we should use it as a launching point for our own independent study.
The “binary numbers” portion of day 1 at UC Baseline. Tap to see at full size.
There was a lot of introductory material to cover on day one of the Hardware 101 portion of the program, and there’s one bit of basic but important material that I think deserves a closer look, especially for my fellow classmates who’ve never had to deal with it before: How binary and hexadecimal numbers are related.
The problem with binary
(for humans, anyway)
Consider the population of Florida. According to the U.S. Census Bureau, on July 1, 2019, that number was estimated to be 21,477,737 in base 10, a.k.a. the decimal system.
Here’s the same number, expressed in base 2, a.k.a. the binary system: 1010001111011100101101001.
That’s the problem with binary numbers: Because they use only two digits, 0 and 1, they grow in length extremely quickly, which makes them hard for humans to read. Can you tell the difference between 100000000000000000000000 and 1000000000000000000000000? Be careful, because those two numbers are significantly different — one is twice the size of the other!
(Think about it: In the decimal system, you make a number ten times as large by tacking a 0 onto the end. For the exact same reason, tacking a 0 onto the end of binary number doubles that number.)
Hexadecimal is an easier way to write binary numbers
Once again, the problem is that:
Binary numbers, because they use only two digits — 0 and 1 — get really long really quickly, and
Decimal numbers don’t convert easily to binary.
What we need is a numerical system that:
Can represent really big numbers with relatively few characters, and
Converts easily to binary.
Luckily for us, there’s a numerical system that fits this description: Hexadecimal. The root words for hexadecimal are hexa (Greek for “six”) and decimal (from Latin for “ten”), and it means base 16.
Using 4 binary digits, you can represent the numbers 0 through 15:
Decimal
Binary
0
0000
1
0001
2
0010
3
0011
4
0100
5
0101
6
0110
7
0111
8
1000
9
1001
10
1010
11
1011
12
1100
13
1101
14
1110
15
1111
Hexadecimal is the answer to the question “What if we had a set of digits that represented the 16 numbers of 0 through 15?”
Let’s repeat the above table, this time with hexadecimal digits:
Decimal
Binary
Hexadecimal
0
0000
0
1
0001
1
2
0010
2
3
0011
3
4
0100
4
5
0101
5
6
0110
6
7
0111
7
8
1000
8
9
1001
9
10
1010
A
11
1011
B
12
1100
C
13
1101
D
14
1110
E
15
1111
F
Hexadecimal gives us easier-to-read numbers where each digit represents a group of 4 binary digits. Because of this, it’s easy to convert back and forth between binary and hexadecimal.
Since we’re creatures of base 10, we have the single characters to represent the digits 0 through 9, but no single character to represent 10, 11, 12, 13, 14, and 15, which are digits in hexadecimal. To work around this problem, hexadecimal uses the first 6 letters from the Roman alphabet: A, B, C, D, E, and F.
That’s a hard number to read, and if you had to manually enter it, the odds are pretty good that you’d make a mistake. Let’s convert it to its hexadecimal equivalent.
We do this by first breaking that binary number into groups of 4 bits (remember, a single hexadecimal number represents 4 bits, and “bit” is a portmanteau for “binary digit”):
1100 0010 1010 1001
Now let’s use the table above to look up the hexadecimal digit for each of those groups of 4:
1100 0010 1010 1001
C 2 A 9
There you have it:
The decimal representation of the number is 49,833,
How to indicate if you’re writing a number in decimal, binary, or hexadecimal form
Because we’re base 10 creatures, we simply write decimal numbers as-is:
49,833
To indicate that a number is in binary, we prefix it with the number zero followed by a lowercase b:
0b1100001010101001
This is a convention used in many programming languages. Try it for yourself in JavaScript:
# This will print "49833" in the console
console.log(0b1100001010101001)
Or if you prefer, Python:
# This will print "49833" in the console
print(0b1100001010101001)
To indicate that a number is in hexadecimal, we prefix it with the number zero followed by a lowercase x:
oxC2A9
Once again, try it for yourself in JavaScript:
# This will print "49833" in the console
print(0xc2a9)
print(0xC2A9)
Or Python:
# Both of these will print "49833" in the console
print(0xc2a9)
print(0xC2A9)
Common grouping of binary numbers and hexadecimal
4 bits: A half-byte, tetrade, or nybble
A single hexadecimal digit represents 4 bits, and my favorite term for a group of 4 bits is nybble. The 4 bits that make up a nybble can represent the numbers 0 through 15.
“Nybble” is one of those computer science-y jokes that’s based on the fact that a group of 8 bits is called a byte. I’ve seen the terms half-byte and tetrade also used.
8 bits: A byte
Two hexadecimal digits represent 8 bits, and a group of 8 bits is called a byte. The 8 bits that make up a byte can represent the numbers 0 through 255, or the numbers -128 through 127.
In the era of the first general-purpose microprocessors, the data bus was 8 bits wide, and so byte was the standard unit of data. Every character in the ASCII character set can be expressed in a single byte. Each of the 4 numbers in an IPv4 address is a byte.
16 bits: A word
Four hexadecimal digits represent 16 bits, and a group of 16 bits is most often called a word. The 16 bits that make up a word can represent the numbers 0 through 65,535 (a number sometimes referred to as “64K”), or the numbers -32,768 through 32,767.
If you were computing in the late ’80s or early ’90s — the era covered by Windows 1 through 3 or Macs in the classic chassis — you were using a 16-bit machine. That meant that it stored data a word at a time.
32 bits: A double word or DWORD
Eight hexadecimal digits represent 32 bits, and a group of 32 bits is often called a double word or DWORD; I’ve also heard the unimaginative term “32-bit word”. The 32 bits that make up a word can represent the numbers 0 through 4,294,967,295 (a number sometimes referred to as “4 gigs”), or the numbers −2,147,483,648 through 2,147,483,647.
32-bit operating systems and computers came about in the mid-1990s. Some are still in use today, although they’d now be considered older or “legacy” systems.
The IPv4 address system uses 32 bits, which means that it can represent a maximum of 4,294,967,29 internet addresses. That’s fewer addresses than there are people on earth, and as you might expect, we’re running out of these addresses. There are all manner of workarounds, but the real solution is for everyone to switch to IPv6, which uses 128 bits, which allows for over 3 × 1038 addresses — enough to assign 100 addresses to every atom on the surface of the earth.
64 bits: A quadruple word or QWORD
16 hexadecimal digits represent 64 bits, and a group of 64 bits is often called a quadruple word, quad word, or QWORD; I’ve also heard the unimaginative term “64-bit word”. The 64 bits that make up a word can represent the numbers 0 through 18,446,744,073,709,551,615 (about 18.4 quintillion), or the numbers -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 (minus 9.2 quintillion through 9.2 quintillion).
If you have a Mac and it dates from 2007 or later, it’s probably a 64-bit machine. macOS has supported 32- and 64-bit applications, but from macOS Catalina (which came out in 2019) onward, it’s 64-bit only. As for Windows-based machines, if your processor is an Intel Core 2/i3/i5/i7/i9 or AMD Athlon 64/Opteron/Sempron/Turion 64/Phenom/Athlon II/Phenom II/FX/Ryzen/Epyc, you have a 64-bit processor.
Need more explanation?
The Khan Academy has a pretty good explainer of the decimal, binary, and hexadecimal number systems:
The online Intro to Python Coding course that I’m teaching on behalf of Tampa Bay’s own Computer Coach Training Center starts tonight at 6:00 p.m.. For the next five weeks, on Monday and Wednesday evenings from 6:00 to 10:00, I’ll be leading a class of Python learners through “code along with me” exercises in the Python programming language.
Dropping code science at BarCamp.
The format of the course will be pretty much the same as the one I use at Tampa iOS Meetup, where I lead the group through a “code along with me” exercise. I project what’s on my computer on the big screen, and everyone follows along, entering the code as I explain what’s happening.
Since Python has a REPL (Read-Evaluate-Print Loop), I can also have the class go through some exercises and try little coding challenges. It will be a “learn by doing” kind of class.
In order to minimize confusion, we’ll all use the same tools in the course, namely the Anaconda Individual Edition distribution of Python 3.7 and associated tools……and Visual Studio Code:
Both are available free of charge, and run on macOS, Windows, and Linux.
It’ll be fun! Watch this space; I’ll post some snippets from the course as it progresses.
Interested in signing up? Visit Computer Coach’s site and speak to them. Don’t dawdle — it starts tonight!
When: Monday and Wednesday evenings, 6:00 – 10:00 p.m., starting Monday, July 13 and ending Wednesday, August 12 (6 weeks, twice a week)
Where: Online.
How much: $900 — and Computer Coach has grants that can cover the cost if you’re unemployed and based in the Tampa Bay area (contact them to see if you qualify)
What you’ll need:
A computer that was made sometime in the last ten years. My main computer is a 2014-era MacBook Pro, but I’ll be doing demonstrations on a 2012-era Lenovo ThinkPad running Linux Mint, a 2009-era Compaq laptop running Peppermint Linux, and a $35 Raspberry Pi.
An internet connection. This is an online course, after all.
This is not a passive course! This isn’t the kind of course where the instructor lectures over slides while you take notes (or pretend to take notes while surfing the web or checking your social media feeds). In this course, you’ll be actively taking part in the learning process, entering code, experimenting, making mistakes, correcting those mistakes, and producing working applications. You will learn by doing. At the end of each session, you’ll have a collection of little Python programs that you wrote, and which you can use as the basis for your own work.
The course will start at the most basic level by walking you through the process of downloading and installing the necessary tools to start Python programming. From there, you’ll learn the building blocks of the Python programming language:
Control structures that determine what your programs do,
Data structures to store the information that your programs act on,
Functions and objects to organize your code, and
Using libraries as building blocks for your applications.
You’ll write all sorts of programs…
You’ll use Python in “immediate mode” to perform quick calculations (and you’ll sharpen your command-line skills in the process).
You’ll write scripts to simplify or automate tedious tasks.
You’ll build web applications.
And since it’s a networked, data-driven world where no application is an island, you’ll learn how to use Python to interact with web services and databases.
Better still, you’ll learn how to think like a programmer. You’ll learn how to look at a goal and learn how you could write a program to meet it, and how that program could be improved or enhanced. You’ll learn skills that will serve you well as you take up other programming languages, and even learn a little bit about the inner workings of computers, operating systems, and the internet.
Open a Swift playground in Xcode and enter the following code:
let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
let number = 87654
let spelledOutNumber = formatter.string(for: NSNumber(integerLiteral: number))!
print("\(number) spelled out is \(spelledOutNumber).")
Run the playground code, and you’ll see this:
87654 spelled out is eighty-seven thousand six hundred fifty-four.
Having come from the world of C, where you format strings using printf() and formatting strings, and later from other languages where you use whatever formatting method its string class provides, I’ve ignored most of Swift’s classes that derive from Formatter — with one notable exception: DateFormatter, which is indispensable when working with dates and times.
I’m now looking for an excuse to use this capability.
As I typed “DateFormatter” a couple of paragraphs above, I remembered that DateFormatter had a locale property. It’s for ensuring that any dates you present are in the correct form for the locale:
I wondered:
Does NumberFormatter have a locale property?
What happens if I changed it to something other than my system’s default of US English?
So I changed the code in my playground to the following:
let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
formatter.locale = Locale(identifier: "fil_PH")
let number = 87654
let spelledOutNumber = formatter.string(for: NSNumber(integerLiteral: number))!
print("\(number) spelled out in Filipino is \(spelledOutNumber).")
I ran the code and saw this…
87654 spelled out in Filipino is walóng pû’t pitóng libó’t anim na daán at limáng pû’t ápat.
…and my response was “Ay nako!” (translation: OMG!)
How about Korean?
let formatter = NumberFormatter()
formatter.numberStyle = .spellOut
formatter.locale = Locale(identifier: "ko_KR")
let number = 87654
let spelledOutNumber = formatter.string(for: NSNumber(integerLiteral: number))!
print("\(number) spelled out in Korean is \(spelledOutNumber).")
The output:
87654 spelled out in Korean is 팔만칠천육백오십사.
My response: 세상에 (“Sesange!”, which is pretty much Korean for OMG!)
Last night was the final night of the Intro to Python Coding course that I’ve been teaching on behalf of Computer Coach for the past five weeks — Mondays and Wednesdays, 6:00 p.m. to 10:00 p.m..
Julia has a whole set of zines, some of which are free…
…and some fancier ones, which come at a reasonable price, even for groups:
