NAME¶

std::strstreambuf::str - std::strstreambuf::str

Synopsis¶

char* str() const;

Calls freeze(), then returns a copy of start pointer of the get area,
std::streambuf::eback().

The start of the get area, for all writeable std::strstreambuf objects constructed
through the interface provided by std::strstream, is also the start of the put area.

Parameters¶

(none)

Return value¶

A copy of eback(), which may be a null pointer.

Notes¶

This function is typically called through the std::strstream interface.

The call to freeze() guarantees that the returned pointer remains valid until the
next explicit call to freeze(false): otherwise (on a dynamic buffer) any output
operation could trigger buffer reallocation which would invalidate the pointer. It
also causes a memory leak in the destructor of std::strstreambuf, unless
freeze(false) is called before the buffer (or, more commonly, the std::strstream
that manages it) is destroyed.

Example¶

// Run this code

#include <strstream>
#include <iostream>

int main()
{
std::strstream dyn; // dynamically-allocated read/write buffer
dyn << "Test: " << 1.23 << std::ends;
std::strstreambuf* buf = dyn.rdbuf();
std::cout << "R/W buffer holds \"" << buf->str() // or dyn.str()
<< "\"\n";
dyn.freeze(false); // after calling .str() on a dynamic strstream

char arr[10];
std::ostrstream user(arr, 10); // fixed-size write-only buffer
buf = user.rdbuf();
user << 1.23 << std::ends;
std::cout << "Write-only buffer holds \"" << buf->str() // or user.str()
<< "\"\n";

std::istrstream lit("1 2 3"); // fixed-size read-only buffer
buf = lit.rdbuf();
std::cout << "Read-only buffer holds \"" << buf->str() // or lit.str()
<< "\"\n";
}

Output:¶

R/W buffer holds "Test: 1.23"
Write-only buffer holds "1.23"
Read-only buffer holds "1 2 31 2 3"

See also¶

str accesses the output buffer
(public member function of std::strstream)
str accesses the output buffer
(public member function of std::ostrstream)
str accesses the output buffer
(public member function of std::istrstream)