std::basic_stringbuf<CharT,Traits,Allocator>::init_buf_ptrs

 

C++

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Standard library

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Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

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Metaprogramming library (C++11)

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Technical specifications

Symbols index

External libraries

 

Input/output library

I/O manipulators

Print functions (C++23)

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

basic_spanbuf (C++23)

strstreambuf (C++98/26*)

basic_syncbuf (C++20)

Streams

Abstractions

ios_base

basic_ios

basic_istream

basic_ostream

basic_iostream

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basic_ifstream

basic_ofstream

basic_fstream

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basic_istringstream

basic_ostringstream

basic_stringstream

Array I/O

basic_ispanstream (C++23)

basic_ospanstream (C++23)

basic_spanstream (C++23)

istrstream (C++98/26*)

ostrstream (C++98/26*)

strstream (C++98/26*)

Synchronized Output

basic_osyncstream (C++20)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

 

std::basic_stringbuf

Public member functions

basic_stringbuf::basic_stringbuf

basic_stringbuf::operator= (C++11)

basic_stringbuf::swap (C++11)

basic_stringbuf::str

basic_stringbuf::get_allocator (C++20)

basic_stringbuf::view (C++20)

Protected member functions

basic_stringbuf::underflow

basic_stringbuf::pbackfail

basic_stringbuf::overflow

basic_stringbuf::setbuf

basic_stringbuf::seekoff

basic_stringbuf::seekpos

Non-member functions

swap(std::basic_stringbuf) (C++11)

Exposition-only member functions

basic_stringbuf::init_buf_ptrs

 

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.

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.data() + buf.size(), buf.data() + buf.capacity()).

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

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() + buf.data() for streams that are both input and output streams	makes pptr() == pbase() + buf.size() for append streams