c - 纯头文件 ANSI C 库如何可能？

Question

有一个非常受欢迎的库，名为 nuklear它都是用 ANSI C 编写的，并且完全只是头文件。然而，每个翻译单元中只能有一个函数定义，并且 ANSI C 没有内联函数，那么这个库如何正常工作而不出现链接器错误呢？

Answer 1

从第 73 行开始是有关如何使用此 header 的说明:

/// ## Usage
/// This library is self contained in one single header file and can be used either
/// in header only mode or in implementation mode. The header only mode is used
/// by default when included and allows including this header in other headers
/// and does not contain the actual implementation. <br /><br />
///
/// The implementation mode requires to define  the preprocessor macro
/// NK_IMPLEMENTATION in *one* .c/.cpp file before #includeing this file, e.g.:
///
/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~C
///     #define NK_IMPLEMENTATION
///     #include "nuklear.h"
/// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

所以通常包含这个头文件只会给你声明。如果您在包含之前#define NK_IMPLMENTATION，则包含该实现。