Notes, thoughts, or questions that arose as I implemented the solutions. Hopefully I am able to go back and answer these questions as I keep learning!

# Things I like

* [Continue expressions](https://zig-by-example.com/while)

# Things that I've found missing from this language

I mean, Jesus Christ, right now it seems even worse than GoLang.

* [String concatenation](https://old.reddit.com/r/Zig/comments/bfcsul/concatenating_zig_strings/)
* [String equality](https://nofmal.github.io/zig-with-example/string-handling/#string-equal)

# Questions

## (From Ziglings)

[Problem 40](https://codeberg.org/ziglings/exercises/src/commit/8da60edb82b25ac913033b2f0edb63eea212c0d0/exercises/040_pointers2.zig) says "_You can always make a const pointer to a mutable value (var), but you cannot make a var pointer to an immutable value (const)._" - which, sure, fair enough (I mean, not really, but I'm not going to argue with it...), but that's not what's presented in the problem - the original code is:

```
    const a: u8 = 12;
    const b: *u8 = &a; // fix this!
```

which is a constant pointer to a _constant_ value - which shouldn't be an issue?

## What's the idiomatic way to run Zig tests?

I've tried - using references like [this](https://zig.guide/build-system/zig-build), [this](https://old.reddit.com/r/Zig/comments/y65qa6/how_to_test_every_file_in_a_simple_zig_project/), and [this](https://www.openmymind.net/Using-A-Custom-Test-Runner-In-Zig/) - to set up `build.zig` so that I could run `zig build test` and thus run every test in my files, but that didn't work:

```zig
// build.zig
const std = @import("std");

pub fn build(b: *std.Build) void {
    const main_tests = b.addTest(.{ .root_source_file = b.path("main.zig") });
    const build_mode = b.standardReleaseOptions();
    main_tests.setBuildMode(build_mode);

    const test_step = b.step("test", "Run library tests");
    test_step.dependOn(&main_tests.step);
}

// main.zig
pub const one = @import("solutions/01.zig");

test {
    @import("std").testing.refAllDecls(@This());
}
```

As-written, `zig build test` gives:

```
/Users/scubbo/Code/advent-of-code-2024/build.zig:19:25: error: no field or member function named 'standardReleaseOptions' in 'Build'
    const build_mode = b.standardReleaseOptions();
```

With that line (and the following one deleted), `zig build test` completes silently, even with a failing test.

And this setup _still_ isn't great, because it's necessary to manually import every file to `main.zig`'s imports.

Hence the `test.sh` workaround script. It's not great, because it will error-out on the first failure (rather than accumulating failures from all files) - but it does the job!

Refer to [here](https://ziglang.org/documentation/master/#Zig-Test) for more info - which I only found after writing that hacky script.

## Why can't a string-literal be passed to a function that accepts a `[]8`?

That is, why is this illegal?

```
fn doIt(string: []u8) []u8 {
    return "prefix" + string;
}

const expect = @import("std").testing.expect;

test {
    expect(std.mem.eql(u8, doIt("foo"), "prefixfoo"))
}
```

I can fix it by changing the type signature to accept `[]const u8`, but (I think?) that then means that I can't call the function with non-const-length strings - including strings read from files.

[This](https://stackoverflow.com/questions/72736997/how-to-pass-a-c-string-into-a-zig-function-expecting-a-zig-string) link refers to `[]const u8` as a "Zig-style string-slice", but also refers to `[*c]const u8` as a "c_string", so...:shrug:?