Difference between revisions of "cpp/io/basic stringbuf"

Latest revision as of 23:01, 5 September 2023

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 character.

(since C++11)

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>

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

[edit] Protected member functions

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

[edit] Non-member functions

std::swap(std::basic_stringbuf)

(C++11)

specializes the std::swap algorithm
(function template) [edit]

Inherited from std::basic_streambuf

Member types

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

Member functions

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

Protected member functions

(constructor)	constructs a `basic_streambuf` object (protected member function) [edit]
operator= (C++11)	replaces a `basic_streambuf` object (protected member function) [edit]
swap (C++11)	swaps two `basic_streambuf` objects (protected member function) [edit]
Locales
imbue [virtual]	changes the associated locale (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Positioning
setbuf [virtual]	replaces the buffer with user-defined array, if permitted (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
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>`) [edit]
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>`) [edit]
sync [virtual]	synchronizes the buffers with the associated character sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
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>`) [edit]
underflow [virtual]	reads characters from the associated input sequence to the get area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
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>`) [edit]
xsgetn [virtual]	reads multiple characters from the input sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
ebackgptregptr	returns a pointer to the beginning, current character and the end of the get area (protected member function) [edit]
gbump	advances the next pointer in the input sequence (protected member function) [edit]
setg	repositions the beginning, next, and end pointers of the input sequence (protected member function) [edit]
Put area
xsputn [virtual]	writes multiple characters to the output sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
overflow [virtual]	writes characters to the associated output sequence from the put area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pbasepptrepptr	returns a pointer to the beginning, current character and the end of the put area (protected member function) [edit]
pbump	advances the next pointer of the output sequence (protected member function) [edit]
setp	repositions the beginning, next, and end pointers of the output sequence (protected member function) [edit]
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>`) [edit]

@@ Line 1: / Line 1: @@
 {{cpp/title|basic_stringbuf}}
-{{cpp/io/basic_stringbuf/sidebar}}
+{{cpp/io/basic_stringbuf/navbar}}
-<code>
+{{ddcl|header=sstream|1=
-#include <sstream>
+template<
+    class CharT,
+    class Traits = std::char_traits<CharT>,
+    class Allocator = std::allocator<CharT>
+> class basic_stringbuf
+    : public std::basic_streambuf<CharT, Traits>
+}}
-template<
+{{tt|std::basic_stringbuf}} is a {{lc|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 {{lc|std::basic_string}}.
-    class charT,
-    class Traits = char_traits<charT>,
-    class Allocator = allocator<charT>
-> class basic_stringbuf;          //inherits basic_streambuf<charT, Traits, Allocator>
-</code>
-Two specializations for common character types are also defined:
+Typical implementations of {{tt|std::basic_stringbuf}} hold an object of type {{lc|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 {{lc|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).
-<code>
+In addition, a typical implementation holds a data member of type {{lc|std::ios_base::openmode}} to indicate the I/O mode of the associated stream (input-only, output-only, input/output, at-end, etc).
-typedef basic_stringbuf<char> stringbuf;
+{{rrev|since=c++11|If over-allocation strategy is used by {{lc|overflow()}}, an additional high-watermark pointer may be stored to track the last initialized character.}}
-typedef basic_stringbuf<wchar_t> wstringbuf;
-</code>
-[[/todo]]
+{{cpp/basic char typedefs|stringbuf|sstream}}
 ===Member types===
+{{dsc begin}}
+{{dsc hitem|Member type|Definition}}
+{{dsc inc|cpp/io/dsc char_type}}
+{{dsc inc|cpp/io/dsc traits_type}}
+{{dsc inc|cpp/io/dsc int_type}}
+{{dsc inc|cpp/io/dsc pos_type}}
+{{dsc inc|cpp/io/dsc off_type}}
+{{dsc inc|cpp/io/dsc allocator_type}}
+{{dsc end}}
-^ Member type ^ Definition ^
+===Exposition-only members===
-| ''char_type'' | ''charT'' |
+{{dsc begin}}
-| ''traits_type'' | ''Traits'' |
+{{dsc expos mem obj|buf|the {{c/core|std::basic_string<CharT, Traits, Allocator>}} used as the underlying buffer}}
-| ''int_type'' | ''Traits::int_type'' |
+{{dsc expos mem obj|mode|the {{lc|std::ios_base::openmode}} of the associated stream}}
-| ''pos_type'' | ''Traits::pos_type'' |
+{{dsc expos mem fun|cpp/io/basic_stringbuf/init_buf_ptrs|initializes the input and output sequences}}
-| ''off_type'' | ''Traits::off_type'' |
+{{dsc end}}
-| ''allocator_type'' | ''Allocator'' ([[/C++0x]] feature) |
-===Member functions===
+===Public member functions===
+{{dsc begin}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc constructor}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc operator{{=}}}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc swap}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc destructor}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc str}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc get_allocator}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc view}}
+{{dsc end}}
-[[/todo]]
+===Protected member functions===
+{{dsc begin}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc underflow}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc pbackfail}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc overflow}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc setbuf}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc seekoff}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc seekpos}}
+{{dsc end}}
-====See also====
+===Non-member functions===
+{{dsc begin}}
+{{dsc inc|cpp/io/basic_stringbuf/dsc swap2}}
+{{dsc end}}
-[[/io/basic_streambuf/]], [[/io/basic_filebuf/]]
+{{cpp/io/basic_streambuf/inherit}}
+{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

Compiler support
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Feature test macros (C++20)
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Ranges library (C++20)
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Technical specifications
Symbols index
External libraries

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
File I/O
basic_ifstream
basic_ofstream
basic_fstream
String I/O
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)

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

`buf`	the std::basic_string<CharT, Traits, Allocator> used as the underlying 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*)

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Difference between revisions of "cpp/io/basic stringbuf"

Latest revision as of 23:01, 5 September 2023

Contents

[edit] Member types

[edit] Exposition-only members

[edit] Public member functions

[edit] Protected member functions

[edit] Non-member functions

Inherited from std::basic_streambuf

Member types

Member functions

Locales

Positioning

Get area

Put area

Putback