check_bool
check_bool(isalnum(s[j]), iswalnum(c), '1');
check_bool(isalpha(s[j]), iswalpha(c), '2');
check_bool(isblank(s[j]), iswblank(c), '3');
check_bool(iscntrl(s[j]), iswcntrl(c), '4');
check_bool(isdigit(s[j]), iswdigit(c), '5');
check_bool(isgraph(s[j]), iswgraph(c), '6');
check_bool(islower(s[j]), iswlower(c), '6');
check_bool(isprint(s[j]), iswprint(c), '7');
check_bool(ispunct(s[j]), iswpunct(c), '8');
check_bool(isspace(s[j]), iswspace(c), '9');
check_bool(isupper(s[j]), iswupper(c), 'a');
check_bool(isxdigit(s[j]), iswxdigit(c), 'b');
check_bool(isalnum(i), iswalnum(i), '1');
check_bool(isalpha(i), iswalpha(i), '2');
check_bool(isblank(i), iswblank(i), '3');
check_bool(iscntrl(i), iswcntrl(i), '4');
check_bool(isdigit(i), iswdigit(i), '5');
check_bool(isgraph(i), iswgraph(i), '6');
check_bool(islower(i), iswlower(i), '6');
check_bool(isprint(i), iswprint(i), '7');
check_bool(ispunct(i), iswpunct(i), '8');
check_bool(isspace(i), iswspace(i), '9');
check_bool(isupper(i), iswupper(i), 'a');
check_bool(isxdigit(i), iswxdigit(i), 'b');