NAME¶

std::strstreambuf - std::strstreambuf

Synopsis¶

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 destructs a strstreambuf object, optionally deallocating the character
[virtual] array
(virtual public member function)
freeze sets/clears the frozen state of the buffer
(public member function)
marks the buffer frozen and returns the beginning pointer of the input
str sequence
(public member function)
returns the next pointer minus the beginning pointer in the output
pcount sequence: the number of characters written
(public member function)

Protected member functions¶

underflow reads a character from the input sequence without advancing the next
[virtual] pointer
(virtual protected member function)
pbackfail backs out the input sequence to unget a character
[virtual] (virtual protected member function)
overflow appends a character to the output sequence, may reallocate or
[virtual] initially allocate the buffer if dynamic and not frozen
(virtual protected member function)
setbuf attempts to replace the controlled character sequence with an array
[virtual] (virtual protected member function)
seekoff repositions the next pointer in the input sequence, output sequence,
[virtual] or both, using relative addressing
(virtual protected member function)
seekpos repositions the next pointer in the input sequence, output sequence,
[virtual] 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 destructs the basic_streambuf object
[virtual] (virtual public member function of
std::basic_streambuf<CharT,Traits>)

Locales¶

invokes imbue()
pubimbue (public member function of std::basic_streambuf<CharT,Traits>)

obtains a copy of the associated locale
getloc (public member function of std::basic_streambuf<CharT,Traits>)

Positioning¶

invokes setbuf()
pubsetbuf (public member function of std::basic_streambuf<CharT,Traits>)

invokes seekoff()
pubseekoff (public member function of std::basic_streambuf<CharT,Traits>)

invokes seekpos()
pubseekpos (public member function of std::basic_streambuf<CharT,Traits>)

invokes sync()
pubsync (public member function of std::basic_streambuf<CharT,Traits>)

Get area¶

obtains the number of characters immediately available in the get
in_avail area
(public member function of std::basic_streambuf<CharT,Traits>)

advances the input sequence, then reads one character without
snextc advancing again
(public member function of std::basic_streambuf<CharT,Traits>)

sbumpc reads one character from the input sequence and advances the
stossc sequence
(removed in C++17) (public member function of std::basic_streambuf<CharT,Traits>)

reads one character from the input sequence without advancing the
sgetc sequence
(public member function of std::basic_streambuf<CharT,Traits>)

invokes xsgetn()
sgetn (public member function of std::basic_streambuf<CharT,Traits>)

Put area¶

writes one character to the put area and advances the next
sputc pointer
(public member function of std::basic_streambuf<CharT,Traits>)

invokes xsputn()
sputn (public member function of std::basic_streambuf<CharT,Traits>)

Putback¶

puts one character back in the input sequence
sputbackc (public member function of std::basic_streambuf<CharT,Traits>)

moves the next pointer in the input sequence back by one
sungetc (public member function of std::basic_streambuf<CharT,Traits>)

Protected member functions¶

constructor constructs a basic_streambuf object
(protected member function)
operator= replaces a basic_streambuf object
(C++11) (protected member function)
swap swaps two basic_streambuf objects
(C++11) (protected member function)

Locales¶

imbue changes the associated locale
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)

Positioning¶

setbuf replaces the buffer with user-defined array, if permitted
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
repositions the next pointer in the input sequence, output sequence,
seekoff or both, using relative addressing
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
repositions the next pointer in the input sequence, output sequence,
seekpos or both using absolute addressing
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
sync synchronizes the buffers with the associated character sequence
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)

Get area¶

obtains the number of characters available for input in the associated
showmanyc input sequence, if known
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
underflow reads characters from the associated input sequence to the get area
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
reads characters from the associated input sequence to the get area
uflow and advances the next pointer
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
xsgetn reads multiple characters from the input sequence
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
eback returns a pointer to the beginning, current character and the end of
gptr the get area
egptr (protected member function)
gbump advances the next pointer in the input sequence
(protected member function)
repositions the beginning, next, and end pointers of the input
setg sequence
(protected member function)

Put area¶

xsputn writes multiple characters to the output sequence
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
overflow writes characters to the associated output sequence from the put area
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)
pbase returns a pointer to the beginning, current character and the end of
pptr the put area
epptr (protected member function)
pbump advances the next pointer of the output sequence
(protected member function)
repositions the beginning, next, and end pointers of the output
setp sequence
(protected member function)

Putback¶

puts a character back into the input sequence, possibly modifying the
pbackfail input sequence
[virtual] (virtual protected member function of
std::basic_streambuf<CharT,Traits>)