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类型是 comptime 值

像处理其他值一样处理类型。

类型是 comptime 值 是 CoddyKit 上的免费 Zig Academy 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Zig Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Zig Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

A Type Is Just a Value

In Zig a type is not magic syntax: it is an ordinary value you can store, pass, and return. It simply lives only at compile-time. 🧠

The type of a Type Is type

Every type has the type type. So u8 is a value whose type is type, just like 5 is a value whose type is an integer.

const T: type = u8;

Bind a Type to a const

You can name a type with a constant. Here Number becomes another name for i32 that you can use wherever a type is expected.

const Number = i32;
const x: Number = 7;

Pass a Type to a Function

A function can take a type as a comptime parameter. The argument is a real value, evaluated while the program compiles.

fn sizeOf(comptime T: type) usize {
    return @sizeOf(T);
}

Return a Type from a Function

Because types are values, a function can return one. Its return type is just type, and the body produces a type as its result.

fn Pair() type {
    return struct { a: u8, b: u8 };
}

This Is How Generics Work

Passing and returning types is the foundation of Zig generics. There is no special generic syntax, just type values flowing around.

Types Live Only at Compile-Time

A value of type type exists only during compilation. You cannot store a type in a run-time variable or read one from input.

Inspect a Type with Builtins

Built-ins treat a type as data. @sizeOf takes a type value and returns how many bytes one instance of it occupies.

const bytes = @sizeOf(u32);

Compare Types for Equality

Since types are values, you can compare them at compile-time. The expression T == u8 is true only when T is exactly u8.

Choose a Type at Compile-Time

You can branch on a type and pick another, all during compilation. This lets one function adapt its behavior to the type it gets.

Name a Type from a Function Result

Since a function can return a type, you can bind that result to a constant and then use it just like any built-in type name.

const Point = Pair();
const p: Point = .{ .a = 1, .b = 2 };

Quick Check

In Zig, what is the type of the type u8 itself?

Recap

Types in Zig are comptime values of type type. You can name, pass, return, and compare them, which is exactly how generics are built. 🎯

常见问题解答

「类型是 comptime 值」课时是免费的吗？

是的 — 「类型是 comptime 值」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Zig Academy 课程的其余内容，请升级到 CoddyKit PRO。 Zig Academy 课程共包含 4 节课。

「类型是 comptime 值」这节课中我会学到什么？

像处理其他值一样处理类型。你通过在浏览器中直接运行的动手代码来练习 Zig Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Zig Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Zig Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「类型是 comptime 值」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Zig Academy 课中编写并运行代码吗？

能。每节 Zig Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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