> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man9/ctassert.9.md). # CTASSERT.9 `CTASSERT` — 编译时断言宏 ## 名称 `CTASSERT` ## 概要 ```c #include #include ``` ```c CTASSERT(expression); ``` ## 描述 `CTASSERT` 宏已弃用，应使用 C11 标准的 `_Static_assert` 替代。应包含头文件 `sys/cdefs.h` 以提供对 C11 之前编译器的兼容性。 `CTASSERT` 宏在编译时评估 `expression`，如果为假则导致编译器错误。 `CTASSERT` 宏可用于在编译期间断言重要数据结构和变量的大小或对齐方式，否则这些问题只会在运行时导致代码失败。 ## 实例 断言 `uuid` 结构的大小为 16 字节。 ```c CTASSERT(sizeof(struct uuid) == 16); ``` ## 参见 [KASSERT(9)](/man/man9/kassert.9.md) ## 作者 本手册页由 Hiten M. Pandya 编写。 --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://book.bsdcn.org/man/man9/ctassert.9.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.