Converts from a pointer to position within a string to a integer character offset. Since 2.10, this function allows pos to be before str, and returns a negative offset in this case.
a UTF-8 encoded string
a pointer to a position within str
the resulting character offset
See Implementation
Converts from a pointer to position within a string to a integer character offset. Since 2.10, this function allows pos to be before str, and returns a negative offset in this case.