//en.cppreference.com/w/c/string/wide/wcschr.html
#include <wchar.h>
#include <stdio.h>
#include <locale.h>
int main(void)
{
wchar_t arr[] = L"白猫 黒猫 кошки";
wchar_t *cat = wcschr(arr, L'猫');
wchar_t *dog = wcschr(arr, L'犬');
setlocale(LC_ALL, "en_US.utf8");
if(cat)
printf("The character 猫 found at position %td\n", cat-arr);
else
puts("The character 猫 not found");
if(dog)
printf("The character 犬 found at position %td\n", dog-arr);
else
puts("The character 犬 not found");
}