Difference between revisions of "cpp/io/strstreambuf"
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m (in C++98) |
m (→Notes: P2867R1, mention `spanbuf`.) |
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{{cpp/title|strstreambuf}} | {{cpp/title|strstreambuf}} | ||
{{cpp/io/strstreambuf/navbar}} | {{cpp/io/strstreambuf/navbar}} | ||
| − | {{ddcl | header=strstream | deprecated=c++98 | | + | {{ddcl|header=strstream|deprecated=c++98|removed=c++26|1= |
class strstreambuf : public std::basic_streambuf<char> | class strstreambuf : public std::basic_streambuf<char> | ||
}} | }} | ||
| − | {{tt|std::strstreambuf}} is a {{lc|std::basic_streambuf}} whose associated character sequence is a character array, which may be constant (e.g. a string literal), | + | {{tt|std::strstreambuf}} is a {{lc|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 {{tt|std::strstreambuf}} may be allowed to reallocate the array as necessary to accommodate output (e.g. by calling {{c/core|delete[]}} and {{c/core|new[]}} or user-provided functions). |
Typical implementation of a {{tt|std::strstreambuf}} holds four private data members: | Typical implementation of a {{tt|std::strstreambuf}} holds four private data members: | ||
| Line 15: | Line 15: | ||
===Notes=== | ===Notes=== | ||
| − | After any call to {{ | + | After any call to {{lc|str()}} on a stream with a dynamic buffer, a call to {{lc|freeze()|freeze(false)}} is required to allow the {{tt|strstreambuf}} destructor to deallocate the buffer when necessary. |
| + | |||
| + | {{tt|strstreambuf}} has been deprecated since C++98 and removed since C++26{{rev inl|since=c++23|. The recommended replacement is {{ltt|cpp/io/basic_spanbuf|std::spanbuf}}}}. | ||
===Member functions=== | ===Member functions=== | ||
{{dsc begin}} | {{dsc begin}} | ||
| − | {{dsc h1 | Public member functions}} | + | {{dsc h1|Public member functions}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc strstreambuf}} | + | {{dsc inc|cpp/io/strstreambuf/dsc strstreambuf}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc ~strstreambuf}} | + | {{dsc inc|cpp/io/strstreambuf/dsc ~strstreambuf}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc freeze}} | + | {{dsc inc|cpp/io/strstreambuf/dsc freeze}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc str}} | + | {{dsc inc|cpp/io/strstreambuf/dsc str}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc pcount}} | + | {{dsc inc|cpp/io/strstreambuf/dsc pcount}} |
| − | {{dsc h1 | Protected member functions}} | + | {{dsc h1|Protected member functions}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc underflow}} | + | {{dsc inc|cpp/io/strstreambuf/dsc underflow}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc pbackfail}} | + | {{dsc inc|cpp/io/strstreambuf/dsc pbackfail}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc overflow}} | + | {{dsc inc|cpp/io/strstreambuf/dsc overflow}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc setbuf}} | + | {{dsc inc|cpp/io/strstreambuf/dsc setbuf}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc seekoff}} | + | {{dsc inc|cpp/io/strstreambuf/dsc seekoff}} |
| − | {{dsc inc | cpp/io/strstreambuf/dsc seekpos}} | + | {{dsc inc|cpp/io/strstreambuf/dsc seekpos}} |
{{dsc end}} | {{dsc end}} | ||
Latest revision as of 07:22, 6 April 2024
| 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.
Contents |
[edit] 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).
[edit] Member functions
Public member functions | |
constructs a strstreambuf object (public member function) | |
| [virtual] |
destructs a strstreambuf object, optionally deallocating the character array (virtual public member function) |
| sets/clears the frozen state of the buffer (public member function) | |
| marks the buffer frozen and returns the beginning pointer of the input sequence (public member function) | |
| returns the next pointer minus the beginning pointer in the output sequence: the number of characters written (public member function) | |
Protected member functions | |
| [virtual] |
reads a character from the input sequence without advancing the next pointer (virtual protected member function) |
| [virtual] |
backs out the input sequence to unget a character (virtual protected member function) |
| [virtual] |
appends a character to the output sequence, may reallocate or initially allocate the buffer if dynamic and not frozen (virtual protected member function) |
| [virtual] |
attempts to replace the controlled character sequence with an array (virtual protected member function) |
| [virtual] |
repositions the next pointer in the input sequence, output sequence, or both, using relative addressing (virtual protected member function) |
| [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
| [virtual] |
destructs the basic_streambuf object (virtual public member function of std::basic_streambuf<CharT,Traits>)
|
Locales | |
| invokes imbue() (public member function of std::basic_streambuf<CharT,Traits>)
| |
| obtains a copy of the associated locale (public member function of std::basic_streambuf<CharT,Traits>)
| |
Positioning | |
| invokes setbuf() (public member function of std::basic_streambuf<CharT,Traits>)
| |
| invokes seekoff() (public member function of std::basic_streambuf<CharT,Traits>)
| |
| invokes seekpos() (public member function of std::basic_streambuf<CharT,Traits>)
| |
| invokes sync() (public member function of std::basic_streambuf<CharT,Traits>)
| |
Get area | |
| obtains the number of characters immediately available in the get area (public member function of std::basic_streambuf<CharT,Traits>)
| |
| advances the input sequence, then reads one character without advancing again (public member function of std::basic_streambuf<CharT,Traits>)
| |
| (removed in C++17) |
reads one character from the input sequence and advances the sequence (public member function of std::basic_streambuf<CharT,Traits>)
|
| reads one character from the input sequence without advancing the sequence (public member function of std::basic_streambuf<CharT,Traits>)
| |
| invokes xsgetn() (public member function of std::basic_streambuf<CharT,Traits>)
| |
Put area | |
| writes one character to the put area and advances the next pointer (public member function of std::basic_streambuf<CharT,Traits>)
| |
| invokes xsputn() (public member function of std::basic_streambuf<CharT,Traits>)
| |
Putback | |
| puts one character back in the input sequence (public member function of std::basic_streambuf<CharT,Traits>)
| |
| moves the next pointer in the input sequence back by one (public member function of std::basic_streambuf<CharT,Traits>)
| |
Protected member functions
constructs a basic_streambuf object (protected member function) | |
| (C++11) |
replaces a basic_streambuf object (protected member function) |
| (C++11) |
swaps two basic_streambuf objects (protected member function) |
Locales | |
| [virtual] |
changes the associated locale (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
Positioning | |
| [virtual] |
replaces the buffer with user-defined array, if permitted (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
| [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>)
|
| [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>)
|
| [virtual] |
synchronizes the buffers with the associated character sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
Get area | |
| [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>)
|
| [virtual] |
reads characters from the associated input sequence to the get area (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
| [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>)
|
| [virtual] |
reads multiple characters from the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
| returns a pointer to the beginning, current character and the end of the get area (protected member function) | |
| advances the next pointer in the input sequence (protected member function) | |
| repositions the beginning, next, and end pointers of the input sequence (protected member function) | |
Put area | |
| [virtual] |
writes multiple characters to the output sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
| [virtual] |
writes characters to the associated output sequence from the put area (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
| returns a pointer to the beginning, current character and the end of the put area (protected member function) | |
| advances the next pointer of the output sequence (protected member function) | |
| repositions the beginning, next, and end pointers of the output sequence (protected member function) | |
Putback | |
| [virtual] |
puts a character back into the input sequence, possibly modifying the input sequence (virtual protected member function of std::basic_streambuf<CharT,Traits>)
|
