cpp/io/basic streambuf/overflow

Ensures that there is space at the put area for at least one character by saving some initial subsequence of characters starting at pbase to the output sequence and updating the pointers to the put area (if needed). If is not  (i.e. ), it is either put to the put area or directly saved to the output sequence.

The function may update, and  pointers to define the location to write more data. On failure, the function ensures that either or.

The base class version of the function does nothing. The derived classes may override this function to allow updates to the put area in the case of exhaustion.

Return value
Returns unspecified value not equal to on success,  on failure.

The base class version of the function returns.

Note
The sputc and sputn call this function in case of an overflow ( or ).