NAME¶

std::ostrstream::freeze - std::ostrstream::freeze

Synopsis¶

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¶

freeze sets/clears the frozen state of the buffer
(public member function of std::strstreambuf)