| I/O manipulators | ||||
| Print functions(C++23) | ||||
| C-style I/O | ||||
| Buffers | ||||
(C++23) | ||||
(C++98/26*) | ||||
(C++20) | ||||
| Streams | ||||
| Abstractions | ||||
| File I/O | ||||
| String I/O | ||||
| Array I/O | ||||
(C++23) | ||||
(C++23) | ||||
(C++23) | ||||
(C++98/26*) | ||||
(C++98/26*) | ||||
(C++98/26*) | ||||
| Synchronized Output | ||||
(C++20) | ||||
| Types | ||||
| Error category interface | ||||
(C++11) | ||||
(C++11) |
| Public member functions | ||||
strstreambuf::freeze | ||||
| Protected member functions | ||||
void freeze(bool freezefl=true); | (deprecated in C++98) (removed in C++26) | |
If the buffer uses dynamic allocation, sets the frozen status of the stream tofreezefl.
While the stream is frozen,overflow() will not reallocate the buffer and thedestructor will not deallocate the buffer (thereby causing a memory leak).
Contents |
| freezefl | - | new value to set the freeze status to |
(none)
Every call tostr() freezes the stream to preserve the validity of the pointer it returns. To allow the destructor to deallocate the buffer,freeze(false) needs to be called explicitly.
In this example, initial allocation of the underlying array was for 16 bytes.
#include <iostream>#include <strstream> int main(){{std::strstream dyn;// dynamically-allocated read/write buffer dyn<<"Test: "<<1.23;// note: no std::ends to demonstrate append behaviorstd::cout<<"dynamic buffer holds "<< dyn.pcount()<<" characters: '";std::cout.write(dyn.str(), dyn.pcount())<<"'\n";// the buffer is now frozen, further output will not make the buffer grow dyn<<"more output, hopefully enough to run out of the allocated space"<<std::ends;std::cout<<"After more output, it holds "<< dyn.pcount()<<" characters: '"<< dyn.str()<<"'\n"; dyn.freeze(false);// unfreeze before destructor}// memory freed by the destructor {char arr[20];std::ostrstream st(arr, sizeof arr);// fixed-size buffer st<<1.23;// note: no std::ends to demonstrate append behaviorstd::cout<<"static buffer holds "<< st.pcount()<<" characters: '";std::cout.write(st.str(), st.pcount());std::cout<<"'\n"; st<<"more output, hopefully enough to run out of the allocated space"<<std::ends;std::cout<<"static buffer holds "<< st.pcount()<<" characters: '";std::cout.write(st.str(), st.pcount());std::cout<<"'\n";}// nothing to deallocate, no need to unfreeze,}
Output:
dynamic buffer holds 10 characters: 'Test: 1.23'After more output, it holds 16 characters: 'Test: 1.23more o'static buffer holds 4 characters: '1.23'static buffer holds 20 characters: '1.23more output, hop'
| disables/enables automatic reallocation (public member function of std::strstream)[edit] | |
| disables/enables automatic reallocation (public member function of std::ostrstream)[edit] | |
[virtual] | destructs astrstreambuf object, optionally deallocating the character array(virtual public member function)[edit] |
[virtual] | appends a character to the output sequence, may reallocate or initially allocate the buffer if dynamic and not frozen (virtual protected member function)[edit] |
