Having a string type that has "invalid string" value which is different from empty string value is a bliss. What is important there is that the invalid string

Having a string type that has "invalid string" value which is different from empty string value is a bliss. What is important there is that the invalid string value is completely compatible with most C functions - despite actual data pointer is NULL, the length of data is zero so memcmp, memmove/memcpy and most other functions will not segfault. This is really thought out approach. Thank you!