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| -rw-r--r-- | 35_enums.zig | 49 | ||||
| -rw-r--r-- | 36_enums2.zig | 61 | ||||
| -rw-r--r-- | README.md | 24 | ||||
| -rwxr-xr-x | ziglings | 2 |
4 files changed, 131 insertions, 5 deletions
diff --git a/35_enums.zig b/35_enums.zig new file mode 100644 index 0000000..cf455a4 --- /dev/null +++ b/35_enums.zig @@ -0,0 +1,49 @@ +// +// Remember that little mathematical virtual machine we made using the +// "unreachable" statement? Well, there were two problems with the +// way we were using op codes: +// +// 1. Having to remember op codes by number is no good. +// 2. We had to use "unreachable" because Zig had no way of knowing +// how many valid op codes there were. +// +// An "enum" is a Zig construct that lets you give names to numeric +// values and store them in a set. They look a lot like error sets: +// +// const Fruit = enum{ apple, pear, orange }; +// +// const my_fruit = Fruit.apple; +// +// Let's use an enum in place of the numbers we were using in the +// previous version! +// +const std = @import("std"); + +// Please complete the enum! +const Ops = enum{ ??? }; + +pub fn main() void { + const operations = [_]Ops{ + Ops.inc, + Ops.inc, + Ops.inc, + Ops.pow, + Ops.dec, + Ops.dec + }; + + var current_value: u32 = 0; + + for (operations) |op| { + switch (op) { + Ops.inc => { current_value += 1; }, + Ops.dec => { current_value -= 1; }, + Ops.pow => { current_value *= current_value; }, + // No "else" needed! Why is that? + } + + std.debug.print("{} ", .{current_value}); + } + + std.debug.print("\n", .{}); +} diff --git a/36_enums2.zig b/36_enums2.zig new file mode 100644 index 0000000..2e04415 --- /dev/null +++ b/36_enums2.zig @@ -0,0 +1,61 @@ +// +// Enums are really just a set of numbers. You can leave the +// numbering up to the compiler, or you can assign them +// explicitly. You can even specify the numeric type used. +// +// const Stuff = enum(u8){ foo = 16 }; +// +// You can get the integer out with a built-in function: +// +// var my_stuff: u8 = @enumToInt(Stuff.foo); +// +// Note how that built-in function starts with "@" just like the +// @import() function we've been using. +// +const std = @import("std"); + +// Zig lets us write integers in hexadecimal format: +// +// 0xf (is the value 15 in hex) +// +// Web browsers let us specify colors using a hexadecimal +// number where each byte represents the brightness of the +// Red, Green, or Blue component (RGB) where two hex digits +// are one byte with a value range of 0-255: +// +// #RRGGBB +// +// Please define and use a pure blue value Color: +const Color = enum(u32){ + red = 0xff0000, + green = 0x00ff00, + blue = ???, +}; + +pub fn main() void { + // Remeber Zig's multi-line strings? Here they are again. + // Also, check out this cool format string: + // + // {x:0>6} + // ^ + // x type ('x' is lower-case hexadecimal) + // : separator (needed for format syntax) + // 0 padding character (default is ' ') + // > alignment ('>' aligns right) + // 6 width (use padding to force width) + // + // Please add this formatting to the blue value. + // (Even better, experiment without it, or try parts of it + // to see what prints!) + std.debug.print( + \\<p> + \\ <span style="color: #{x:0>6}">Red</span> + \\ <span style="color: #{x:0>6}">Green</span> + \\ <span style="color: #{}">Blue</span> + \\</p> + , .{ + @enumToInt(Color.red), + @enumToInt(Color.green), + @enumToInt(???), // Oops! We're missing something! + }); +} @@ -9,6 +9,18 @@ This project was directly inspired by the brilliant and fun [rustlings](https://github.com/rust-lang/rustlings) project for the [Rust](https://www.rust-lang.org/) language. +## Intended Audience + +This will probably be quite difficult if you've _never_ programmed before. +However, no specific programming experience is required. And in particular, +you are _not_ expected to know C or other "systems programming" language. + +Each exercise is self-contained and self-explained. However, you're encouraged +to also check out these Zig language resources for more detail: + +* https://ziglearn.org/ +* https://ziglang.org/documentation/master/ + ## Getting Started _Note: This currently uses a shell (Bash) script to automate the "game". A @@ -53,7 +65,7 @@ the learning resource I wished for. There will be tons of room for improvement: * Wording of explanations * Idiomatic usage of Zig * Additional exercises -* Re-write the `ziglings` script using the Zig build system (???) +* Re-write the `ziglings` script using the Zig build system (or just a Zig application) Planned exercises: @@ -70,13 +82,13 @@ Planned exercises: * [x] Defer (and errdefer) * [x] Switch * [x] Unreachable +* [x] Enums +* [ ] Structs +* [ ] Unions * [ ] Pointers * [ ] Pointer sized integers * [ ] Multi pointers * [ ] Slices -* [ ] Enums -* [ ] Structs -* [ ] Unions * [ ] Integer rules * [ ] Floats * [ ] Labelled blocks @@ -91,4 +103,6 @@ Planned exercises: * [ ] Imports The initial topics for these exercises were unabashedly cribbed from -[ziglearn.org](https://ziglearn.org/). +[ziglearn.org](https://ziglearn.org/). I've since moved things around +in an order that I think best lets each topic build upon each other. + @@ -102,6 +102,8 @@ check_it 31_switch2.zig "ZIG!" check_it 32_unreachable.zig "1 2 3 9 8 7" check_it 33_iferror.zig "2<4. 3<4. 4=4. 5>4. 6>4." "Seriously, what's the deal with fours?" check_it 34_quiz4.zig "my_num=42" "Can you make this work?" +check_it 35_enums.zig "1 2 3 9 8 7" "This problem seems familiar..." +check_it 36_enums2.zig "#0000ff" "I'm feeling blue about this." echo echo " __ __ _ " |