Zig Academy · 课时

比较和搜索字节

在字符串上使用 std.mem 辅助函数。

比较和搜索字节 是 CoddyKit 上的免费 Zig 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 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。

You Cannot Use ==

Two slices are different windows, so == compares pointers and lengths, not contents. Comparing text needs a real byte-by-byte check.

std.mem to the Rescue

The standard library module std.mem works on slices of any element type, and that includes your []const u8 strings.

const std = @import("std");
const mem = std.mem;

eql Compares Contents

Use mem.eql to test whether two slices hold the same bytes in the same order. It returns a plain bool you can branch on.

mem.eql(u8, "zig", "zig"); // true

Pass the Element Type

Many std.mem helpers take the element type as their first argument. For strings that argument is always u8, matching []const u8.

Find a Substring

Search for text inside text with indexOf. It returns an optional index: the position of the first match, or null if absent.

mem.indexOf(u8, "hello", "ll"); // 2

Handle the null

Because indexOf returns an optional, unwrap it with if or orelse. A null result simply means the needle was not found.

if (mem.indexOf(u8, h, n)) |i| {
    // found at i
}

Search from the End

Need the last occurrence instead of the first? Reach for lastIndexOf, which scans backward and returns an optional index too.

Prefix and Suffix

Check how a string begins or ends with startsWith and endsWith. Both take u8 and return a clean bool, perfect for parsing.

mem.startsWith(u8, "main.zig", "main");

Single-Byte Search

To locate one byte rather than a substring, use indexOfScalar. It is the fast path when you only need a single character.

mem.indexOfScalar(u8, "a,b", ',');

Count Occurrences

Use mem.count to tally how many times a needle appears in the text. It returns a usize, never null, even when the count is zero.

mem.count(u8, "aaa", "a"); // 3

Case Sensitivity

These helpers are case-sensitive: A and a are different bytes. Normalize case first if you want a case-insensitive match.

Quick Check

You want to know if two strings contain exactly the same text.

Recap

You compared text with mem.eql and searched it using indexOf, startsWith, indexOfScalar, and count, all aware of null and case. 🔍

常见问题解答

「比较和搜索字节」课时是免费的吗？

是的 — 「比较和搜索字节」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。

「比较和搜索字节」这节课中我会学到什么？

在字符串上使用 std.mem 辅助函数。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 3 节课，共 4 节。

「比较和搜索字节」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