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HarmonyOS
The C standard library (libc) provides standard header files and common library implementations (such as input/output processing and string handling) in C language programming.
HarmonyOS uses musl as the libc. musl is a lightweight, fast, simple, and free open-source libc. For details, see musl libc Reference Manual.
For details about the differences between musl and glibc, see Functional differences from glibc.
C11 is implemented by libc, libm, and libdl.
libc: provides thread-related interfaces and a majority of standard interfaces.
libm: provides mathematical library interfaces. Currently, HarmonyOS provides a link to libm, and the interfaces are defined in libc.
libdl: provides dynamic linker interfaces such as dlopen. Currently, HarmonyOS provides a link to libdl, and the interfaces are defined in libc.
1.2.0
1.2.3 since HarmonyOS 4.0
1.2.5 since HarmonyOS 5.0
HarmonyOS provides header files and library interfaces that align with C99, C11, and POSIX standards, though not fully compliant. It supports Armv7-A, Arm64, and x86_64 architectures.
To better accommodate the basic features of HarmonyOS devices, such as high performance, low memory usage, high security, lightweight design, and multi-device adaptability, the musl library has been optimized and enhanced, with interfaces unsuitable for embedded devices removed according.
| API | Description |
|---|---|
| epoll_create | In HarmonyOS 5.0, this API uses the same logic as in musl 1.2.3. Specifically, the API does not verify input parameters or process them if the input parameter value is less than or equal to 0. In the next version, this API will adopt the logic from musl 1.2.5, which includes input parameter verification. If the input parameter value is less than or equal to 0, the error code EINVAL will be returned. |
The following lists the character encoding formats and aliases supported by musl.
The character conversion can be successful only when the source character encoding format is correct and the target character encoding format is supported.
musl does not support the following target encoding formats: gb18030, gbk, gb2312, big5, and euckr.
| Encoding Format | Alias | Supported by musl |
|---|---|---|
| utf8 | Yes | |
| wchart | Yes | |
| ucs2be | Yes | |
| ucs2le | Yes | |
| utf16be | Yes | |
| utf16le | Yes | |
| ucs4be | utf32be | Yes |
| ucs4le | utf32le | Yes |
| ascii | usascii, iso646, iso646us | Yes |
| utf16 | Yes | |
| ucs4 | utf32 | Yes |
| ucs2 | Yes | |
| eucjp | Yes | |
| shiftjis | sjis, cp932 | Yes |
| iso2022jp | Yes | |
| gb18030 | Yes | |
| gbk | Yes | |
| gb2312 | Yes | |
| big5 | bigfive, cp950, big5hkscs | Yes |
| euckr | ksc5601, ksx1001, cp949 | Yes |
| iso88591 | latin1 | Yes |
| iso88592 | Yes | |
| iso88593 | Yes | |
| iso88594 | Yes | |
| iso88595 | Yes | |
| iso88596 | Yes | |
| iso88597 | Yes | |
| iso88598 | Yes | |
| iso88599 | Yes | |
| iso885910 | Yes | |
| iso885911 | tis620 | Yes |
| iso885913 | Yes | |
| iso885914 | Yes | |
| iso885915 | latin9 | Yes |
| iso885916 | Yes | |
| cp1250 | windows1250 | Yes |
| cp1251 | windows1251 | Yes |
| cp1252 | windows1252 | Yes |
| cp1253 | windows1253 | Yes |
| cp1254 | windows1254 | Yes |
| cp1255 | windows1255 | Yes |
| cp1256 | windows1256 | Yes |
| cp1257 | windows1257 | Yes |
| cp1258 | windows1258 | Yes |
| koi8r | Yes | |
| koi8u | Yes | |
| cp437 | Yes | |
| cp850 | Yes | |
| cp866 | Yes | |
| cp1047 | ibm1047 | Yes |
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