< cpp‎ | io‎ | basic stringbuf
void init_buf_ptrs();
(exposition only*)

Initializes the input and output sequences from buf according to mode. buf and mode are exposition-only data members of *this.

Immediately after this function returns:

  • If std::ios_base::out is set in mode, pbase() points to buf.front() and epptr() >= pbase() + buf.size() is true;
    • in addition, if std::ios_base::ate is set in mode, pptr() == pbase() + buf.size() is true,
    • otherwise pptr() == pbase() is true.
  • If std::ios_base::in is set in mode, eback() points to buf.front(), and gptr() == eback() && egptr() == eback() + buf.size() is true.

[edit] Notes

For efficiency reasons, stream buffer operations can violate invariants of buf while it is held encapsulated in the std::basic_stringbuf, e.g., by writing to characters in the range [ + buf.size() + buf.capacity()).

All operations retrieving a std::basic_string from buf ensure that the std::basic_string invariants hold on the returned value.

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 1448 C++98 calling init_buf_ptrs() made
pptr() == pbase() +
for streams that are both input and output streams
pptr() == pbase() + buf.size()
for append streams