text: #include <stdio.h>
  #include <wctype.h>
  
  int main()
  {
      int i = 0;
      wchar_t str[] = L"Test String.\n";
      wchar_t c;
      wctype_t check = wctype("lower");
      wctrans_t trans = wctrans("toupper");
      while (str[i])
      {
          c = str[i];
          if (iswctype(c, check))
              c = towctrans(c, trans);
          putwchar(c);
          i++;
      }
      return 0;
  }