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使用 for 和 range 迭代

遍历数字和序列

使用 for 和 range 迭代 是 CoddyKit 上的免费 Mojo 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 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。

Walk Over Items

When you want to visit each value in turn, reach for a for loop. It pulls one item at a time and runs the body for each. 🚶

The for Shape

Write for, a loop variable, the word in, something to walk over, then a colon and an indented block.

for item in things:
    print(item)

Count with range

To loop a fixed number of times, pair for with range. range(n) yields 0 up to but not including n.

for i in range(3):
    print(i)

range Stops Before the End

This catches beginners: range(5) gives 0, 1, 2, 3, 4. The end value is excluded, so you get exactly five numbers.

Choose a Start

Give range two values to set a start and end. range(2, 5) walks 2, 3, 4, beginning where you tell it.

for i in range(2, 5):
    print(i)

Add a Step

A third value sets the step between numbers. range(0, 10, 2) yields the even numbers 0, 2, 4, 6, 8.

for i in range(0, 10, 2):
    print(i)

Count Downward

A negative step lets range go backward. range(3, 0, -1) produces 3, 2, 1, perfect for a simple countdown.

for i in range(3, 0, -1):
    print(i)

Loop Over a List

for works on collections too. Iterating a List hands you each element directly, so you rarely need an index.

for name in names:
    print(name)

Index When You Need It

If you do need positions, loop over range(len(items)) and use the index to reach into the collection.

for i in range(len(items)):
    print(items[i])

Accumulate Across a for

Just like while, a for loop can build a total. Initialize before the loop, then add inside the body each pass.

var total = 0
for i in range(1, 5):
    total += i

Prefer for for Known Counts

Use for with range when the number of passes is known up front. It is clearer and harder to break than a manual while.

Quick Check

You write for i in range(5). Which exact sequence of numbers does i take across the loop?

Recap

A for loop visits each item, and range generates numbers with start, end, and step. Remember the end value is excluded. 🎯

常见问题解答

「使用 for 和 range 迭代」课时是免费的吗？

是的 — 「使用 for 和 range 迭代」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 for 和 range 迭代」这节课中我会学到什么？

遍历数字和序列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 3 节课，共 4 节。

「使用 for 和 range 迭代」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。

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