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使用 var 声明值

在 Mojo 中创建具名变量

使用 var 声明值 是 CoddyKit 上的免费 Mojo 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 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。

Why You Need Names

A program juggles many values. To reuse one later you give it a name. In Mojo you create a named value with var. 📦

Your First var

Write var, then a name, then = and a value. Mojo stores the value under that name so you can use it again.

var score = 100

Reading the Value Back

Once declared, use the name anywhere you want that value. Here score stands in for 100 when you print it.

var score = 100
print(score)

Names Hold Things You Compute

A var does not have to be a literal. You can name the result of an expression so the math happens once.

var total = 100 + 50
print(total)

Changing a var Later

A var is mutable: assign a new value any time without repeating var. The name simply points at its latest value.

var score = 100
score = 250

Choose Clear Names

Good names describe the value. Prefer user_age over x so your code reads like plain English later.

var user_age = 30

snake_case Style

Mojo names use lowercase words joined by underscores, called snake_case. It matches Python and keeps code tidy.

var first_name = "Ada"

Declare Before You Use

You must create a name before reading it. Using a name Mojo has never seen is an error, which catches typos early.

One Name, One Value at a Time

A var holds a single value. Reassigning replaces the old one entirely, so the previous value is simply gone.

var mode = "easy"
mode = "hard"

var Inside a Function

Most vars live inside a function. They exist while the function runs and describe that function's local work.

fn main():
    var greeting = "hi"
    print(greeting)

var Makes Code Readable

Naming a value once and reusing it beats retyping the same number. A clear var is documentation that runs.

Quick Check

You want to store a number so you can reuse it later in your code. Which keyword declares it?

Recap

Use var to name a value, read it by name, and reassign it later. Clear snake_case names make your code easy to follow. 🎯

常见问题解答

「使用 var 声明值」课时是免费的吗？

是的 — 「使用 var 声明值」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 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 var 声明值」这节课中我会学到什么？

在 Mojo 中创建具名变量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 1 节课，共 4 节。

「使用 var 声明值」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 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

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