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defer 能保证什么

在作用域结束时运行代码。

defer 能保证什么 是 CoddyKit 上的免费 Zig Academy 课时。这是第 1 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。

Cleanup You Can Trust

Almost every program opens something it must later close. Zig gives you defer so that cleanup is never forgotten.

What defer Does

A defer statement schedules a piece of code to run when the surrounding scope ends, no matter how it exits.

defer cleanup();

Write Cleanup Right Away

The big idea: put the cleanup line next to the line that acquires the resource, so the two are impossible to separate.

const file = try open();
defer file.close();

It Runs at Scope Exit

The deferred code does not run immediately. It waits until the scope it lives in finishes, then fires.

{
    defer cleanup();
    work();
}

Works on Every Exit Path

Whether the scope ends normally or you return early from the middle, the deferred code still runs. There is no escape.

defer file.close();
if (bad) return error.Oops;

Errors Do Not Skip It

Even if a try later in the function returns an error, your defer has already been scheduled and will run on the way out.

Any Statement, Not Just Calls

A defer can hold any single statement, including a block, so you can group several cleanup steps together.

defer {
    free(buf);
    log("done");
}

Scopes Beyond Functions

defer is tied to its enclosing scope, which can be a loop body or an if block, not only a whole function.

while (more()) {
    defer step();
}

No Manual Tracking

Without defer you must remember to close on every branch. With it, the compiler runs your cleanup so you cannot forget a path.

Reads Top to Bottom

Because acquire and cleanup sit together, your code reads as a clear story: open, use, and the close is already promised.

The Resource Safety Workhorse

From files to allocations to locks, defer is the everyday tool that keeps Zig programs leak-free and tidy.

Quick Check

When does a deferred statement actually run?

Recap

You met defer: write cleanup beside acquisition, and Zig guarantees it runs when the scope exits on every path. 🧹

常见问题解答

「defer 能保证什么」课时是免费的吗？

是的 — 「defer 能保证什么」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。

「defer 能保证什么」这节课中我会学到什么？

在作用域结束时运行代码。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 1 节课，共 4 节。

「defer 能保证什么」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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