Mojo Academy · 课时

使用 inout 原地变更

允许函数更改调用方的值

使用 inout 原地变更 是 CoddyKit 上的免费 Mojo Academy 课时。这是第 2 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 Mojo Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Mojo 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。

Sometimes You Must Change It

Borrowing only lets you read. But sometimes a function needs to actually modify the caller's value, like bumping a counter. ✏️

Meet inout

The inout convention gives a function mutable access. Changes you make inside are reflected back in the caller's variable.

In and Out

The name says it all: the value goes in, you change it, and the updated value comes back out to the caller. No copy is returned.

Marking a Parameter

You write inout before the parameter name. Now assignments inside the function update the original variable directly.

fn increment(inout n: Int):
    n += 1

Calling It

Pass a variable and watch it change after the call. The function edited the caller's value in place, no return needed.

var count = 5
increment(count)
print(count)  # 6

Must Be Mutable

The argument you pass to an inout parameter must be a mutable var. You cannot hand it a fixed literal or a borrowed value.

Exclusive While Borrowed

While a function holds an inout reference, nothing else may touch that value. This exclusivity rule prevents conflicting edits.

No Hidden Copies

Like borrowing, inout works by reference, so there is no full copy. You get mutation without paying for duplication.

Caller Still Owns It

With inout the caller keeps ownership. The function only borrows mutably for the duration of the call, then hands control back.

When to Choose inout

Use inout when a function's whole job is to update a value the caller will keep using, such as growing a buffer or resetting a field.

Read vs Mutate, Side by Side

So far: borrowed means read-only, inout means read and write. Picking the right one tells readers exactly what a function does.

Quick Check

Let us check what inout enables.

Recap

inout lets a function mutate the caller's value in place, by reference and with no copy. The caller still owns it the whole time. 🎯

常见问题解答

「使用 inout 原地变更」课时是免费的吗？

是的 — 「使用 inout 原地变更」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 Mojo Academy 课程的其余内容，请升级到 CoddyKit PRO。 Mojo Academy 课程共包含 4 节课。

「使用 inout 原地变更」这节课中我会学到什么？

允许函数更改调用方的值你通过在浏览器中直接运行的动手代码来练习 Mojo 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 Mojo Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Mojo 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 2 节课，共 4 节。

「使用 inout 原地变更」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 Mojo Academy 课中编写并运行代码吗？

能。每节 Mojo 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。

此课程中的所有课时

← 返回 Mojo Academy