# stdmchar.h
The older Unicode headers in C (`<wchar.h>`, `<uchar.h>`) have a common problem: they do not tell you how much output buffer space a conversion will need, they do not handle malformed input gracefully, and they do not support transcoding between arbitrary encodings. **`stdmchar.h`** is a proposed C header (part of the C2y/C3x standardisation effort) designed to fix this with a cleaner, safer API.

The proposal includes functions like `mbrtoc8` (multibyte to UTF-8 code unit) and `c8rtomb` (UTF-8 to multibyte), along with higher-level transcoding utilities. The intent is to give C a first-class, encoding-correct Unicode story that does not depend on POSIX extensions like `iconv` or platform-specific APIs.

As of C23, `<stdmchar.h>` is not yet in the standard. It has been discussed in the WG14 C standardisation committee but compilers do not ship it yet. For now, the C11/C17 approach for Unicode transcoding remains `<uchar.h>` with `mbrtoc16`/`mbrtoc32` and their inverses. Code that needs `iconv`-style encoding conversion today typically uses the POSIX `iconv` API or a library like libunistring.

When (and if) standardised, the practical benefit will be portable code for converting between UTF-8 and the platform locale encoding, written once and compiled anywhere without relying on extensions.