std::basic_stringbuf::setbuf

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< cpp‎ | io‎ | basic stringbuf
 
C++
 
Input/output library
 
std::basic_stringbuf
 
protected:
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.

Parameters

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

Return value

this.

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.

Example

Test for the stringstream's setbuf functionality

Run this code
#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';
}

Output: 

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

See also

 invokes setbuf()
(public member function of std::basic_streambuf)
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