NAME¶

std::basic_stringbuf - std::basic_stringbuf

Synopsis¶

Defined in header <sstream>
template<

class CharT,
class Traits = std::char_traits<CharT>,
class Allocator = std::allocator<CharT>
> class basic_stringbuf

: public std::basic_streambuf<CharT, Traits>

std::basic_stringbuf is a std::basic_streambuf whose associated character sequence
is a memory-resident sequence of arbitrary characters, which can be initialized from
or made available as an instance of std::basic_string.

Typical implementations of std::basic_stringbuf hold an object of type
std::basic_string or equivalent resizable sequence container directly as a data
member and use it as both the controlled character sequence (the array where the six
pointers of std::basic_streambuf are pointing to) and as the associated character
sequence (the source of characters for all input operations and the target for the
output).

In addition, a typical implementation holds a data member of type
std::ios_base::openmode to indicate the I/O mode of the associated stream
(input-only, output-only, input/output, at-end, etc).

If over-allocation strategy is used by overflow(), an additional
high-watermark pointer may be stored to track the last initialized (since C++11)
character.

Several typedefs for common character types are provided:

Defined in header <sstream>
Type Definition
std::stringbuf std::basic_stringbuf<char>
std::wstringbuf std::basic_stringbuf<wchar_t>

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
allocator_type Allocator

Exposition-only members

the std::basic_string<CharT, Traits, Allocator> used as the underlying
buf buffer
(exposition-only member object*)
mode the std::ios_base::openmode of the associated stream
(exposition-only member object*)
init_buf_ptrs initializes the input and output sequences
(exposition-only member function*)

Public member functions¶

constructor constructs a basic_stringbuf object
(public member function)
operator= assigns a basic_stringbuf object
(C++11) (public member function)
swap swaps two basic_stringbuf objects
(C++11) (public member function)
destructor destructs a basic_stringbuf object and the string it
[virtual] (implicitly declared) holds
(virtual public member function)
replaces or obtains a copy of the associated
str character string
(public member function)
get_allocator obtains a copy of the allocator associated with the
(C++20) internal sequence container
(public member function)
view obtains a view over the underlying character
(C++20) sequence
(public member function)

Protected member functions¶

underflow returns the next character available in the input sequence
[virtual] (virtual protected member function)
pbackfail puts a character back into the input sequence
[virtual] (virtual protected member function)
overflow appends a character to the output sequence
[virtual] (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, or
[virtual] both, using relative addressing
(virtual protected member function)
seekpos repositions the next pointer in the input sequence, output sequence, or
[virtual] both using absolute addressing
(virtual protected member function)

Non-member functions¶

std::swap(std::basic_stringbuf) specializes the std::swap algorithm
(C++11) (function template)

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>)