NAME¶

std::ostrstream::str - std::ostrstream::str

Synopsis¶

char* str(); (deprecated in C++98)
(removed in C++26)

Returns the pointer to the beginning of the buffer, after freezing it. Effectively
calls rdbuf()->str().

Parameters¶

(none)

Return value¶

Pointer to the beginning of the buffer in the associated std::strstreambuf or a null
pointer if no buffer is available.

Notes¶

Before a call to str() that uses the result as a C-string, the stream buffer must be
null-terminated. Regular output such as with stream << 1.2 does not store a null
terminator, it must be appended explicitly, typically with the manipulator
std::ends.

After a call to str(), dynamic streams become frozen. 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, which may
leave the buffer not null-terminated.

Example¶

// Run this code

#include <iostream>
#include <strstream>

int main()
{
std::ostrstream dyn; // dynamically-allocated output buffer
dyn << "Test: " << 1.23; // not adding std::ends to demonstrate append behavior
std::cout << "The output stream holds \"";
std::cout.write(dyn.str(), dyn.pcount()) << "\"\n";
// the stream is now frozen due to str()
dyn << " More text" << std::ends;
std::cout << "The output stream holds \"";
std::cout.write(dyn.str(), dyn.pcount()) << "\"\n";
dyn.freeze(false);
}

Possible output:¶

The stream holds "Test: 1.23"
The stream holds "Test: 1.23 More "

See also¶

str marks the buffer frozen and returns the beginning pointer of the input sequence
(public member function of std::strstreambuf)