std::strstreambuf

 

C++

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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

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ios_base

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basic_stringstream

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basic_ispanstream (C++23)

basic_ospanstream (C++23)

basic_spanstream (C++23)

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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::strstreambuf

Public member functions

strstreambuf::strstreambuf

strstreambuf::~strstreambuf

strstreambuf::freeze

strstreambuf::str

strstreambuf::pcount

Protected member functions

strstreambuf::underflow

strstreambuf::pbackfail

strstreambuf::overflow

strstreambuf::setbuf

strstreambuf::seekoff

strstreambuf::seekpos

 

Defined in header <strstream>
class strstreambuf : public std::basic_streambuf<char>		(deprecated in C++98) (removed in C++26)

std::strstreambuf is a std::basic_streambuf whose associated character sequence is a character array, which may be constant (e.g. a string literal), modifiable but not dynamic (e.g. a stack-allocated array), or dynamic, in which case the std::strstreambuf may be allowed to reallocate the array as necessary to accommodate output (e.g. by calling delete[] and new[] or user-provided functions).

Typical implementation of a std::strstreambuf holds four private data members:

1) buffer state, a bitmask type which can represent any combination of the four values "allocated" (destructor will deallocate), "constant" (output not allowed), "dynamic" (output may reallocate), or "frozen" (deallocation and reallocation are not allowed)

2) allocated buffer size (the beginning of the buffer does not need a special data member, it may be stored in the inherited pointer eback())

3) pointer to user-provided allocation function

4) pointer to user-provided deallocation function.

Notes

After any call to str() on a stream with a dynamic buffer, a call to freeze(false) is required to allow the strstreambuf destructor to deallocate the buffer when necessary.

strstreambuf has been deprecated since C++98 and removed since C++26. The recommended replacement is std::spanbuf(since C++23).

Member functions

Public member functions
(constructor)	constructs a strstreambuf object (public member function)
(destructor) [virtual]	destructs a strstreambuf object, optionally deallocating the character array (virtual public member function)
freeze	sets/clears the frozen state of the buffer (public member function)
str	marks the buffer frozen and returns the beginning pointer of the input sequence (public member function)
pcount	returns the next pointer minus the beginning pointer in the output sequence: the number of characters written (public member function)
Protected member functions
underflow [virtual]	reads a character from the input sequence without advancing the next pointer (virtual protected member function)
pbackfail [virtual]	backs out the input sequence to unget a character (virtual protected member function)
overflow [virtual]	appends a character to the output sequence, may reallocate or initially allocate the buffer if dynamic and not frozen (virtual protected member function)
setbuf [virtual]	attempts to replace the controlled character sequence with an array (virtual protected member function)
seekoff [virtual]	repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function)
seekpos [virtual]	repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function)

Inherited from std::basic_streambuf

Member types

Member type	Definition
char_type	CharT
traits_type	Traits; the program is ill-formed if Traits::char_type is not CharT.
int_type	Traits::int_type
pos_type	Traits::pos_type
off_type	Traits::off_type

Member functions

(destructor) [virtual]	destructs the basic_streambuf object (virtual public member function of std::basic_streambuf<CharT,Traits>)
Locales
pubimbue	invokes imbue() (public member function of std::basic_streambuf<CharT,Traits>)
getloc	obtains a copy of the associated locale (public member function of std::basic_streambuf<CharT,Traits>)
Positioning
pubsetbuf	invokes setbuf() (public member function of std::basic_streambuf<CharT,Traits>)
pubseekoff	invokes seekoff() (public member function of std::basic_streambuf<CharT,Traits>)
pubseekpos	invokes seekpos() (public member function of std::basic_streambuf<CharT,Traits>)
pubsync	invokes sync() (public member function of std::basic_streambuf<CharT,Traits>)
Get area
in_avail	obtains the number of characters immediately available in the get area (public member function of std::basic_streambuf<CharT,Traits>)
snextc	advances the input sequence, then reads one character without advancing again (public member function of std::basic_streambuf<CharT,Traits>)
sbumpcstossc (removed in C++17)	reads one character from the input sequence and advances the sequence (public member function of std::basic_streambuf<CharT,Traits>)
sgetc	reads one character from the input sequence without advancing the sequence (public member function of std::basic_streambuf<CharT,Traits>)
sgetn	invokes xsgetn() (public member function of std::basic_streambuf<CharT,Traits>)
Put area
sputc	writes one character to the put area and advances the next pointer (public member function of std::basic_streambuf<CharT,Traits>)
sputn	invokes xsputn() (public member function of std::basic_streambuf<CharT,Traits>)
Putback
sputbackc	puts one character back in the input sequence (public member function of std::basic_streambuf<CharT,Traits>)
sungetc	moves the next pointer in the input sequence back by one (public member function of std::basic_streambuf<CharT,Traits>)

Protected member functions

(constructor)	constructs a basic_streambuf object (protected member function)
operator= (C++11)	replaces a basic_streambuf object (protected member function)
swap (C++11)	swaps two basic_streambuf objects (protected member function)
Locales
imbue [virtual]	changes the associated locale (virtual protected member function of std::basic_streambuf<CharT,Traits>)
Positioning
setbuf [virtual]	replaces the buffer with user-defined array, if permitted (virtual protected member function of std::basic_streambuf<CharT,Traits>)
seekoff [virtual]	repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function of std::basic_streambuf<CharT,Traits>)
seekpos [virtual]	repositions the next pointer in the input sequence, output sequence, or both using absolute addressing (virtual protected member function of std::basic_streambuf<CharT,Traits>)
sync [virtual]	synchronizes the buffers with the associated character sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
Get area
showmanyc [virtual]	obtains the number of characters available for input in the associated input sequence, if known (virtual protected member function of std::basic_streambuf<CharT,Traits>)
underflow [virtual]	reads characters from the associated input sequence to the get area (virtual protected member function of std::basic_streambuf<CharT,Traits>)
uflow [virtual]	reads characters from the associated input sequence to the get area and advances the next pointer (virtual protected member function of std::basic_streambuf<CharT,Traits>)
xsgetn [virtual]	reads multiple characters from the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
ebackgptregptr	returns a pointer to the beginning, current character and the end of the get area (protected member function)
gbump	advances the next pointer in the input sequence (protected member function)
setg	repositions the beginning, next, and end pointers of the input sequence (protected member function)
Put area
xsputn [virtual]	writes multiple characters to the output sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
overflow [virtual]	writes characters to the associated output sequence from the put area (virtual protected member function of std::basic_streambuf<CharT,Traits>)
pbasepptrepptr	returns a pointer to the beginning, current character and the end of the put area (protected member function)
pbump	advances the next pointer of the output sequence (protected member function)
setp	repositions the beginning, next, and end pointers of the output sequence (protected member function)
Putback
pbackfail [virtual]	puts a character back into the input sequence, possibly modifying the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)