std::ostrstream::freeze
From cppreference.com
< cpp | io | ostrstream
| void freeze(bool flag = true); |
||
If the stream is using a dynamically-allocated array for output, disables (flag == true) or enables (flag == false) automatic allocation/deallocation of the buffer. Effectively calls rdbuf()->freeze(flag)
Notes
After a call to str(), dynamic streams become frozen automatically. A call to freeze(false) is required before exiting the scope in which this ostrstream object was created. otherwise the destructor will leak memory. Also, additional output to a frozen stream may be truncated once it reaches the end of the allocated buffer.
Parameters
| flag | - | desired status |
Return value
(none)
Example
Run this code
#include <strstream> #include <iostream> int main() { std::ostrstream dyn; // dynamically-allocated output buffer dyn << "Test: " << 1.23; // note: no std::ends to demonstrate appending std::cout << "The output stream contains \""; std::cout.write(dyn.str(), dyn.pcount()) << "\"\n"; // the stream is now frozen due to str() dyn << " More text"; // output to a frozen stream may be truncated std::cout << "The output stream contains \""; std::cout.write(dyn.str(), dyn.pcount()) << "\"\n"; dyn.freeze(false); // freeze(false) must be called or the destructor will leak std::ostrstream dyn2; // dynamically-allocated output buffer dyn2 << "Test: " << 1.23; // note: no std::ends std::cout << "The output stream contains \""; std::cout.write(dyn2.str(), dyn2.pcount()) << "\"\n"; dyn2.freeze(false); // unfreeze the stream after str() dyn2 << " More text" << std::ends; // output will not be truncated (buffer grows) std::cout << "The output stream contains \"" << dyn2.str() << "\"\n"; dyn2.freeze(false); // freeze(false) must be called or the destructor will leak }
Possible output:
The output stream contains "Test: 1.23" The output stream contains "Test: 1.23 More " The output stream contains "Test: 1.23" The output stream contains "Test: 1.23 More text"
See also
| sets/clears the frozen state of the buffer (public member function of std::strstreambuf) |