[c.mb.wcs]

# 28 Text processing library [[text]](./#text)

## 28.7 Null-terminated sequence utilities [[text.c.strings]](text.c.strings#c.mb.wcs)

### 28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13295)

[*Note [1](#note-1)*:

The headers [<cstdlib>](cstdlib.syn#header:%3ccstdlib%3e "17.2.2 Header <cstdlib> synopsis [cstdlib.syn]"),[<cuchar>](cuchar.syn#header:%3ccuchar%3e "28.7.4 Header <cuchar> synopsis [cuchar.syn]"),
and [<cwchar>](cwchar.syn#header:%3ccwchar%3e "28.7.3 Header <cwchar> synopsis [cwchar.syn]") declare the functions described in this subclause[.](#1.sentence-1)

â *end note*]

[ð](#lib:mbsinit)

`int mbsinit(const mbstate_t* ps);
int mblen(const char* s, size_t n);
size_t mbstowcs(wchar_t* pwcs, const char* s, size_t n);
size_t wcstombs(char* s, const wchar_t* pwcs, size_t n);
`

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13315)

*Effects*: These functions have the semantics specified in the C standard library[.](#2.sentence-1)

See also: ISO/IEC 9899:2024, 7.22.7.1, 7.22.8, 7.29.6.2.1

[ð](#lib:mbtowc)

`int mbtowc(wchar_t* pwc, const char* s, size_t n);
int wctomb(char* s, wchar_t wchar);
`

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13330)

*Effects*: These functions have the semantics specified in the C standard library[.](#3.sentence-1)

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13334)

*Remarks*: Calls to these functions
may introduce a data race ([[res.on.data.races]](res.on.data.races "16.4.6.10 Data race avoidance"))
with other calls to the same function[.](#4.sentence-1)

See also: ISO/IEC 9899:2024, 7.22.7

[ð](#itemdecl:3)

`size_t [mbrlen](#lib:mbrlen "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(const char* s, size_t n, mbstate_t* ps);
size_t [mbrtowc](#lib:mbrtowc "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(wchar_t* pwc, const char* s, size_t n, mbstate_t* ps);
size_t [wcrtomb](#lib:wcrtomb "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char* s, wchar_t wc, mbstate_t* ps);
size_t [mbrtoc8](#lib:mbrtoc8 "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char8_t* pc8, const char* s, size_t n, mbstate_t* ps);
size_t [c8rtomb](#lib:c8rtomb "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char* s, char8_t c8, mbstate_t* ps);
size_t [mbrtoc16](#lib:mbrtoc16 "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char16_t* pc16, const char* s, size_t n, mbstate_t* ps);
size_t [c16rtomb](#lib:c16rtomb "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char* s, char16_t c16, mbstate_t* ps);
size_t [mbrtoc32](#lib:mbrtoc32 "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char32_t* pc32, const char* s, size_t n, mbstate_t* ps);
size_t [c32rtomb](#lib:c32rtomb "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char* s, char32_t c32, mbstate_t* ps);
size_t [mbsrtowcs](#lib:mbsrtowcs "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(wchar_t* dst, const char** src, size_t len, mbstate_t* ps);
size_t [wcsrtombs](#lib:wcsrtombs "28.7.5 Multibyte / wide string and character conversion functions [c.mb.wcs]")(char* dst, const wchar_t** src, size_t len, mbstate_t* ps);
`

[5](#5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13358)

*Effects*: These functions have the semantics specified in the C standard library[.](#5.sentence-1)

[6](#6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L13362)

*Remarks*: Calling these functions
with an mbstate_t* argument that is a null pointer value
may introduce a data race ([[res.on.data.races]](res.on.data.races "16.4.6.10 Data race avoidance"))
with other calls to the same function
with an mbstate_t* argument that is a null pointer value[.](#6.sentence-1)

See also: ISO/IEC 9899:2024, 7.30.1, 7.31.6.3, 7.31.6.4
