__stpcpy() copies the string src (including the terminating /0 character) to the array dest. The strings may not overlap, and dest must be large enough to receive the copy.
__stpcpy() returns a pointer to the end of the string dest (that is, the address of the terminating NULL character) rather than the beginning.
__stpcpy() has the same specification as stpcpy().
__stpcpy() is not in the source standard; it is only in the binary standard.