#include <stdio.h>
#include <locale.h>
#include <string.h>
#include <wchar.h>
#include <stdlib.h>
int main(void)
{
setlocale(LC_ALL, "en_US.utf8");
mbstate_t state;
memset(&state, 0, sizeof state);
wchar_t in[] = L"zß水🍌"; size_t in_sz = sizeof in / sizeof *in;
printf("Processing %zu wchar_t units: [ ", in_sz);
for(size_t n = 0; n < in_sz; ++n) printf("%#x ", (unsigned int)in[n]);
puts("]");
char out[MB_CUR_MAX * in_sz];
char *p = out;
for(size_t n = 0; n < in_sz; ++n) {
int rc = wcrtomb(p, in[n], &state);
if(rc == -1) break;
p += rc;
}
size_t out_sz = p - out;
printf("into %zu UTF-8 code units: [ ", out_sz);
for(size_t x = 0; x < out_sz; ++x) printf("%#x ", +(unsigned char)out[x]);
puts("]");
}