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单向链表

节点、所有权与遍历

单向链表 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。

What a Linked List Is

A singly linked list chains values together: each node holds a value and a pointer to the next node, or null at the end. 🔗

Define the Node

A node is a struct with a value and an optional pointer to the next node. Optional means the last node points at null.

const Node = struct {
    value: i32,
    next: ?*Node,
};

Why the Pointer Is Optional

Using ?*Node lets the chain end safely. There is no need for a special sentinel value to mark the tail.

next: ?*Node

The List Tracks the Head

The list itself just remembers the first node, called the head, plus the allocator that owns every node.

const List = struct {
    head: ?*Node,
    alloc: std.mem.Allocator,
};

Allocate One Node

To add a value, ask the allocator to create a single Node on the heap. This returns a pointer to fresh storage.

const node = try self.alloc.create(Node);

Push to the Front

The cheapest insert is at the head: point the new node at the old head, then make it the new head. This is constant time.

node.* = .{ .value = v, .next = self.head };
self.head = node;

Walk the Chain

To traverse, start at head and follow each next pointer until you reach null. A while loop captures the node nicely.

var cur = self.head;
while (cur) |n| {
    std.debug.print("{d}\n", .{n.value});
    cur = n.next;
}

The Capture Unwraps the Optional

Writing while (cur) |n| runs the body only while cur is non-null, and n is the unwrapped pointer. The loop ends at null.

while (cur) |n| { ... }

You Own Every Node

Each node came from the allocator, so each must be returned. Forgetting even one is a leak the testing allocator will report.

Free the Whole List

Walk the chain in deinit, but grab next before freeing, because the node is gone the moment you destroy it.

var cur = self.head;
while (cur) |n| {
    const nxt = n.next;
    self.alloc.destroy(n);
    cur = nxt;
}

Make It Generic

Wrap Node and List in a type-returning function so the list works for any element type, not just i32.

fn LinkedList(comptime T: type) type {
    return struct {
        const Node = struct { value: T, next: ?*Node };
    };
}

Quick Check

You are freeing a linked list node by node. What must you do before destroying each node?

Recap

Nodes hold a value and an optional next pointer. The list tracks the head and an allocator, pushes to the front, and frees node by node. 🎯

常见问题解答

「单向链表」课时是免费的吗？

是的 — 「单向链表」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。

「单向链表」这节课中我会学到什么？

节点、所有权与遍历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。

「单向链表」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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