std::strstreambuf(3)

📦 version 2024.07.05, in nixpkgs unstable, opensuse-leap 16.0

💖 std::strstreambuf 💖

okay bestie, welcome to the std::strstreambuf(3) page from the C++ Standard Library manual 🫶 this one is giving “vintage C++ buffer energy”: deprecated, removed, and still fully iconic in a chaotic way 😭✨

🌸 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. that array can be:

constant, like a string literal 👑
modifiable but not dynamic, like a stack-allocated array 🧚
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:

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) 🧊
allocated buffer size (the beginning of the buffer does not need a special data member, it may be stored in the inherited pointer eback()) 📏
pointer to user-provided allocation function 🛠️
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 😭 this is the “do not forget or the vibe check fails” part.

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

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>)
sbumpc — reads one character from the input sequence and advances the sequence 🚶 (public member function of std::basic_streambuf<CharT,Traits>)
stossc (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>)