#include <stdio.h>
#include <stdlib.h>
#include <locale.h>
int main(void)
{
const wchar_t src[] = L"z\u00df\u6c34\U0001f34c";
char dst[11];
setlocale(LC_ALL, "en_US.utf8");
printf("wide-character string: '%ls'\n",src);
for (size_t ndx=0; ndx < sizeof src/sizeof src[0]; ++ndx)
printf(" src[%2zu] = %#8x\n", ndx, src[ndx]);
int rtn_val = wcstombs(dst, src, sizeof dst);
printf("rtn_val = %d\n", rtn_val);
if (rtn_val > 0)
printf("multibyte string: '%s'\n",dst);
for (size_t ndx=0; ndx<sizeof dst; ++ndx)
printf(" dst[%2zu] = %#2x\n", ndx, (unsigned char)dst[ndx]);
}