< cpp‎ | io‎ | basic stringbuf
virtual std::basic_streambuf<CharT, Traits>* setbuf( char_type* s, std::streamsize n )

If s is a null pointer and n is zero, this function has no effect.

Otherwise, the effect is implementation-defined: some implementations do nothing, while some implementations clear the std::string member currently used as the buffer and begin using the user-supplied character array of size n, whose first element is pointed to by s, as the buffer and the input/output character sequence.

This function is protected virtual, it may only be called through pubsetbuf() or from member functions of a user-defined class derived from std::basic_stringbuf.


[edit] Parameters

s - pointer to the first CharT in the user-provided buffer or null
n - the number of CharT elements in the user-provided buffer or zero

[edit] Return value


[edit] Notes

The deprecated stream buffer std::strstreambuf or the boost.IOStreams device boost::basic_array may be used to implement I/O buffering over a user-provided char array in portable manner.

[edit] Example

Test for the stringstream's setbuf functionality.

#include <iostream>
#include <sstream>
int main()
    std::ostringstream ss;
    char c[1024] = {};
    ss.rdbuf()->pubsetbuf(c, 1024);
    ss << 3.14 << '\n';
    std::cout << c << '\n';


3.14 (on GNU g++/libstdc++ and SunPro C++/roguewave)
<nothing> (on MS Visual Studio 2010, SunPro C++/stlport4, CLang++/libc++)

[edit] See also

invokes setbuf()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]