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### 169. Bad efficiency of `overflow()` mandated

Section: 31.8.2.5 [stringbuf.virtuals] Status: TC1 Submitter: Dietmar Kühl Opened: 1999-07-20 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

Paragraph 8, Notes, of this section seems to mandate an extremely inefficient way of buffer handling for `basic_stringbuf`, especially in view of the restriction that `basic_ostream` member functions are not allowed to use `xsputn()` (see 31.7.6.2 [ostream]): For each character to be inserted, a new buffer is to be created.

Of course, the resolution below requires some handling of simultaneous input and output since it is no longer possible to update `egptr()` whenever `epptr()` is changed. A possible solution is to handle this in `underflow()`.

Proposed resolution:

In 31.8.2.5 [stringbuf.virtuals] paragraph 8, Notes, insert the words "at least" as in the following:

> To make a write position available, the function reallocates (or initially allocates) an array object with a sufficient number of elements to hold the current array object (if any), plus at least one additional write position.