/* assign an empty string */
U8 *str = StrNew("");
/* or */
U8 *str = "";

/* to test if string is empty */
if (StrLen(str) == 0) { ... }
/* or compare to a known empty string. "== 0" means strings are equal */
if (StrCmp(str, "") == 0) { ... }

/* to test if string is not empty */
if (StrLen(str)) { ... }