Understanding the Odin Programming Language

# Understanding the Odin Programming Language Source: [https://odinbook.com/](https://odinbook.com/)  Do you want to learn the Odin Programming Language and demystify low\-level programming? Then this book is for you\. [Read a sample](https://odinbook.com/sample.html)or[buy now](https://store.zylinski.se/b/tnwvO) *Understanding the Odin Programming Language*is a book that teaches both basic and advanced Odin concepts\. You'll learn about procedures,**manual memory management**, parametric polymorphism, data\-oriented design, and much more\. The target audience is anyone with some programming experience\. Odin is a simple yet powerful language, making this book a**great introduction to low\-level programming**, regardless of your background\. A programming language is a tool\.**By understanding your tools, you will become a better craftsperson**\. Therefore, this book does not just explain how to write Odin code\. It also explains*why*the language works the way it does\. **What people say:** > I highly recommend Karl Zylinski's excellently written book on Odin—perfect for anyone who wants to learn and understand the Odin programming language\. \-**Bill "gingerBill" Hall, creator of Odin**\. > Karl makes a great job at explaining Odin\. I had a good experience with garbage collected language like Golang and the book really helped me to transition to a non garbage collected language like Odin\. \-**Review on store\.zylinski\.se by Kevin D**\. > I never read, I get distracted easily\. But the writing style here is so good, that I didn't have any issues reading through the whole thing in a couple days\. \-**Review on store\.zylinski\.se by Shaka**\. **Version 1\.10 released\!**Read the[release notes](https://odinbook.com/#release_notes)\. **Available formats:** ## HTML  Beautifully laid out and easy to navigate\. A portable HTML file with all the fonts and images baked in\. Similar to a PDF, but nicer to use\. The optimal reading experience on a computer\. Can also be read on a phone or tablet\. Available on: [store\.zylinski\.seHTML\+eBook](https://store.zylinski.se/b/tnwvO)[ItchHTML\+eBook](https://zylinski.itch.io/odinbook) [Read a sample](https://odinbook.com/sample.html) **If you are unsure of which version to get, then I recommend buying it from[store\.zylinski\.se](https://store.zylinski.se/b/tnwvO)or[Itch](https://zylinski.itch.io/odinbook)\.**On there you'll get both the HTML and eBook versions\. ## Overview video ## Release notes Version 1\.10- Section 8\.3 has been changed to teach the`\[dynamic; N\]T`type \(Fixed Capacity Dynamic Array\) instead of the`Small\_Array`\. The Fixed Capacity Dynamic Array deprecates the`Small\_Array`\. - Updated Appendix B to also use the Fixed Capacity Dynamic Array\. - Appendix A now has some comments about the handle\-based map that now exists in`core`\. - Minor change in 10\.3 where some unneeded slicing was done\. Get the latest version by just re\-downloading the book from wherever you bought it\. Version 1\.9- Updated usages of`core:os`in order to match the changes introduced by "os2"\. Background: The whole`core:os`package was replaced during February 2026\. After this replacement, some code example changes were needed\. A lot of code that used`core:os`still works, but usages of`os\.read\_entire\_file`and`os\.write\_entire\_file`needed some changes\. - External links in the HTML version now open in a new tab\. - Improve the bubble in 10\.1\.1 about disabling bounds checking\. - Fixed around 30 grammar issues\. - Fixed several minor technical errors\. Version 1\.8### Strings chapter overhaul This version does some major changes to the strings chapter \(chapter 11\)\. It has been heavily revised and expanded\. Some changes are: - Clearer about how UTF\-8 is decoded into runes\. - A section on how to manually decode UTF\-8\. - The old "bubble" about null termination has been made into a proper section\. - The section "Deallocating strings mixed with string constants" has been made clearer and more useful by considering a map instead of an array\. - A section on how the phrase "string constant" can be ambiguous\. - The Windows section on UTF\-16 has been mostly rewritten and now uses the new`cstring16`type\. - Many, many more small changes and edits\. ### Changes to other chapters - Chapter 1\.5: Typo fix\. - Chapter 2\.4: Note about`odin run \. \-keep\-executable`\(new Odin behavior\)\. - Chapter 3\.2: Typo fix abut type inference\. - Chapter 5\.3: Clarification about the`\.\(Type\)`syntax used to check the variant of unions\. - Chapter 7\.4: Clarified a sentence\. - Chapter 7\.8: Add information about "contextless" requirement for`@init`and`@fini`\. - Chapter 10\.1\.5: Code typo fix\. - Chapter 10\.3: Remove unnecessary slice operation\. - Chapter 11\.6: Code typo fix\. - Chapter 15\.2: Move bubble about`bit\_set`initializers to a more appropriate location\. - Chapter 15\.2\.2: Typo fix\. - Chapter 15\.3: Typo fix\. - \.\.\. and several additional small fixes\! Version 1\.7- Chapter 1: Fix broken Discord link - Chapter 5\.1\.3: Typo fix - Chapter 9\.7:`rand\.int\_max`range clarification - Chapter 14\.3: Improved 'Special\_Array' example - Chapter 23: Typo fix - Chapter 26\.6: Fix broken WebGPU example link - Appendix D: Fix compilation error Version 1\.6- New section 17\.5 called "Breaking cyclic dependencies using callbacks", about how to use callbacks to work around situations where you'd need a cyclic dependency and how to create rudimentary interfaces\. - Chapter 13\.1\.2: Updated the tracking allocator examples based on recent changes to how the handling of bad frees work\. - A new section 18\.6 called "More complicated build setups"\. A short section about writing bigger custom build scripts\. - A new section 26\.10 called "Code generation": It just says what code generation is and links to an example\. - Appendix D: Removed some unnecessary things from the the Raylib \+ Box2D sample and made it a bit clearer\. - Added an icon to the HTML version, so it's easier to find the tab\. - Chapter 23\.3: Made it clearer that you don't need to avoid dynamic literals, but you need to understand that they allocate memory\. - Chapter 6\.3: Typo fix - Chapter 8\.1\.3: Fix incorrect direction of the vector`from\_1\_to\_2` - Chapter 8\.1\.4: Consistent use of procedure name`draw\_image`instead of sometimes using`draw\_texture`\. - Chapter 12\.1: Typo fix - Chapter 23\.1: Minor rephrasing for clarity Version 1\.5I have read the whole book, essentially doing an extra editing pass\. I've made a huge amount of changes that make the text clearer\. Here are some of the bigger changes: - Clarification about the size of`My\_Union`in 5\.3 - Use the words "member" and "value" when talking about enums\. Previously I used "enum value" and "value"\. The old wording was confusing and ambiguous\. - Renamed chapter 26 to "A few more things\.\.\." and edited the content a bit\. - Mention`\#load`in chapter 26 - Mention`@rodata`in chapter 26 - A section about "Making libraries compile cleanly" in chapter 26 - New section 7\.8 \(`@init`and`@fini`\) - Section 4\.3 \(Loops\) has been improved\. - Section 6\.3 \(A pointer to a struct\) is now more pedagogical\. - Section 10\.3 \(Custom iterators\) has been improved\. - New section 11\.5\.1 \(Deallocating strings that are mixed with string constants\) - Section 12\.6 \(context\.user\_ptr and context\.user\_index\) has a new example\. - Fix for illustration in 2\.6 having a minor error\. - Move dynamic literals to chapter 23 \(Things in Odin to avoid\) since they are disabled by default, for a good reason\. - Chapter 18: Nuance about "not needing a build system" and what I actually mean when I say "build system"\. - Made a few things in 6\.5 clearer - Fix typos in 5\.1\.3, 5\.2\.1, 6\.5, 10\.2\.1 reported by readers \(thanks\!\) - Added version number to front\. - Fix for YouTube links using wrong "external link" symbol in HTML version\. - Link to CAT & ONION on itch\.io \(since it comes with Odin code\)\. - Mention`\#reverse`in "Chapter 4: Some additional basics" Version 1\.4- Regarding automatic passing as immutable references: Changed "sufficiently large" into "larger than 16 bytes"\. Recently, Odin changed the threshold to always be 16 bytes, regardless of platform\. - Clarified side\-bubble in 6\.2 regarding how many bits of a pointer that are usually used\. - Make it clearer what is meant by "procedure's stack memory" in 8\.1\.2\. - Added a comment in 8\.1\.3 about what "stack allocated array" means and point out that a later chapter will show how to dynamically allocate fixed arrays\. - Fix for EPUB issue where some of the appendices looked weird\. - Minor typo fixes\. Version 1\.3- Fix for EPUB issue where some of the appendices looked weird\. - More nuance in 13\.1\.1 about cleaning up memory allocations at shutdown\. - More nuance in 5\.3\.5 about using Odin for non\-gamedev\. - Clarifications in 3\.2 regarding my sloppy use of the word "decimal"\. - Fixed`level`not being a pointer in 13\.2 and added some info about why it needs to be a pointer\. - Fixed an error in 8\.1\.1 where the index 20 was used instead of index 10\. - Additional typo fixes\. Version 1\.2- New section on Address Sanitizer in chapter 13\. - Fixed 28 different typos and grammar issues based on a list that PythagoRascal sent me\. Thanks\! - Fixed indentation error in`bit\_set`chapter\. - Clarifications about using`bit\_set`versus using a\-set\-that\-is\-a\-map\. - Section on`Small\_Array`has has been improved for clarity\. - Mentioned that Untyped Floats can be implicitly converted to integers if no truncation happens\. - Clarification about how`delete`works\. - Added a bubble that mentioned what`@static`on local variables does\. - Additional typo fixes, some from people on my Discord\. Thanks everyone\! Version 1\.1Released shortly after 1\.0\. Fixes a bunch of typos\. --- ## About the author  Karl Zylinski is an independent game developer and programming educator\. He is the author of Understanding the Odin Programming Language, a book that teaches Odin in an approachable way\. Karl is the creator of the video game[CAT & ONION](https://store.steampowered.com/app/2781210/CAT__ONION/)\. It was the first commercial video game made in the Odin Programming Language\. He also runs[a YouTube channel](https://www.youtube.com/@karl_zylinski)where he shares educational material on Odin and game development\. In the past Karl has worked as a game engine programmer at Our Machinery, Bitsquid and Autodesk\. He has also worked as a game programmer at Hazelight \(A Way Out\) and Friendly Foe \(SOULBOUND\)\. Karl has a bachelor's degree in astrophysics\. In his free time he likes to play video games, hike, go bouldering and play piano\. Visit his website and blog at[zylinski\.se](https://zylinski.se/)\. Chat about Odin and game development on his[Discord server](https://discord.gg/4FsHgtBmFK)\.