mbrtoc32
| Defined in header <uchar.h>
|
||
| (since C11) | ||
Converts a single code point from its narrow multibyte character representation to its variable-length 32-bit wide character representation (but typically, UTF-32).
If s is not a null pointer, inspects at most n bytes of the multibyte character string, beginning with the byte pointed to by s to determine the number of bytes necessary to complete the next multibyte character (including any shift sequences, and taking into account the current multibyte conversion state *ps). If the function determines that the next multibyte character in s is complete and valid, converts it to the corresponding 32-bit wide character and stores it in *pc32 (if pc32 is not null).
If the multibyte character in *s corresponds to a multi-char32_t sequence (not possible with UTF-32), then after the first call to this function, *ps is updated in such a way that the next calls to mbrtoc32 will write out the additional char32_t, without considering *s.
If s is a null pointer, the values of n and pc32 are ignored and the call is equivalent to mbrtoc32(NULL, "", 1, ps).
If the wide character produced is the null character, the conversion state *ps represents the initial shift state.
If the macro __STDC_UTF_32__ is defined, the 32-bit encoding used by this function is UTF-32; otherwise, it is implementation-defined. The macro is always defined and the encoding is always UTF-32. (since C23) In any case, the multibyte character encoding used by this function is specified by the currently active C locale.
Parameters
| pc32 | - | pointer to the location where the resulting 32-bit wide character will be written |
| s | - | pointer to the multibyte character string used as input |
| n | - | limit on the number of bytes in s that can be examined |
| ps | - | pointer to the conversion state object used when interpreting the multibyte string |
Return value
The first of the following that applies:
- 0 if the character converted from
s(and stored in *pc32 if non-null) was the null character - the number of bytes [1...n] of the multibyte character successfully converted from
s - (size_t)-3 if the next char32_t from a multi-char32_t character has now been written to *pc32. No bytes are processed from the input in this case.
- (size_t)-2 if the next
nbytes constitute an incomplete, but so far valid, multibyte character. Nothing is written to *pc32. - (size_t)-1 if encoding error occurs. Nothing is written to
*pc32, the value EILSEQ is stored in errno and the value of *ps is unspecified.
Example
#include <stdio.h> #include <locale.h> #include <string.h> #include <uchar.h> #include <assert.h> int main(void) { setlocale(LC_ALL, "en_US.utf8"); char in[] = u8"zß水🍌"; // or "z\u00df\u6c34\U0001F34C" const size_t in_size = sizeof in / sizeof *in; printf("Processing %zu UTF-8 code units: [ ", in_size); for (size_t i = 0; i < in_size; ++i) printf("0x%02x ", (unsigned char)in[i]); puts("]"); char32_t out[in_size]; char32_t *p_out = out; char *p_in = in, *end = in + in_size; mbstate_t state; memset(&state, 0, sizeof(state)); size_t rc; while ((rc = mbrtoc32(p_out, p_in, end - p_in, &state))) { assert(rc != (size_t)-3); // no surrogate pairs in UTF-32 if (rc == (size_t)-1) break; // invalid input if (rc == (size_t)-2) break; // truncated input p_in += rc; ++p_out; } size_t out_size = p_out+1 - out; printf("into %zu UTF-32 code units: [ ", out_size); for (size_t i = 0; i < out_size; ++i) printf("0x%08X ", out[i]); puts("]"); }
Output:
Processing 11 UTF-8 code units: [ 0x7a 0xc3 0x9f 0xe6 0xb0 0xb4 0xf0 0x9f 0x8d 0x8c 0x00 ] into 5 UTF-32 code units: [ 0x0000007A 0x000000DF 0x00006C34 0x0001F34C 0x00000000 ]
References
- C23 standard (ISO/IEC 9899:2023):
- 7.30.1.5 The mbrtoc32 function (p: 410)
- C17 standard (ISO/IEC 9899:2018):
- 7.28.1.3 The mbrtoc32 function (p: 293-294)
- C11 standard (ISO/IEC 9899:2011):
- 7.28.1.3 The mbrtoc32 function (p: 400-401)
See also
| (C11) |
converts a 32-bit wide character to narrow multibyte string (function) |