std::strstreambuf:: freeze
|
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 to freezefl .
While the stream is frozen,
overflow()
will not reallocate the buffer and the
destructor
will not deallocate the buffer (thereby causing a memory leak).
Parameters
| freezefl | - | new value to set the freeze status to |
Return value
(none)
Notes
Every call to str() 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.
Example
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 behavior std::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 behavior std::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'
See also
|
disables/enables automatic reallocation
(public member function of
std::strstream
)
|
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|
disables/enables automatic reallocation
(public member function of
std::ostrstream
)
|
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[virtual]
|
destructs a
strstreambuf
object, optionally deallocating the character array
(virtual public 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) |