Zig Academy · 课时

使用 var 保存可变状态

了解何时以及如何允许重新赋值。

使用 var 保存可变状态 是 CoddyKit 上的免费 Zig 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 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。

When Values Change

Some values truly need to move: a counter, a running total, a current score. For those, Zig gives you the var keyword.

Meet var

The keyword var creates a mutable binding. Unlike const, the name you declare with var can be reassigned again and again.

var score = 0;

Reassigning Freely

Once a value is a var, updating it is just a plain assignment. No special syntax is needed, only the name and a new value.

var score = 0;
score = 10;

Updating in Place

You can compute a new value from the old one. Adding to a counter is the classic example of useful mutation in a loop.

var count: u32 = 0;
count += 1;

Type Often Needed

For a var that starts at zero, Zig may ask for a type so it knows the integer width. Annotate it once and you are set.

var total: i64 = 0;

Unused Mutation Warns

If you declare a var but never actually change it, Zig warns you. It nudges you to use const instead for a clearer intent.

var Inside Functions

Mutable locals live inside functions and last for that scope. A loop accumulator declared with var is a perfect everyday use.

var sum: u32 = 0;
sum += value;

The Cost of Mutation

Every var is one more thing that can change underfoot. Use it where change is the point, not as a lazy default choice.

Loop Counters

A while loop often drives a var forward each pass. The binding updates, the condition rechecks, and the loop advances.

var i: usize = 0;
while (i < 5) : (i += 1) {}

Same Type, New Value

A var can change its value but never its type. An i32 stays an i32; you cannot suddenly store text in a number binding.

var vs const Recap

Think of it simply: const is a value pinned in place, while var is a value that is meant to move. Reach for var only when it must.

Quick Check

You need a counter that increases inside a loop. Which keyword should declare it?

Recap

You learned that var creates a mutable binding for values that change. Annotate its type when needed, and use it only where mutation is truly the goal. 🔁

常见问题解答

「使用 var 保存可变状态」课时是免费的吗？

是的 — 「使用 var 保存可变状态」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。

「使用 var 保存可变状态」这节课中我会学到什么？

了解何时以及如何允许重新赋值。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 2 节课，共 4 节。

「使用 var 保存可变状态」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。

此课程中的所有课时

← 返回 Zig Academy