std::basic_stringbuf<CharT,Traits,Allocator>:: operator=

1) Move assignment operator: Moves the contents of rhs into * this . After the move, * this has the associated string, the open mode, the locale, and all other state formerly held by rhs . The six pointers of std::basic_streambuf in * this are guaranteed to be different from the corresponding pointers in the moved-from rhs unless null.

2) The copy assignment operator is deleted; basic_stringbuf is not CopyAssignable .

#include <iostream>
#include <sstream>
#include <string>
 
int main()
{
    std::istringstream one("one");
    std::ostringstream two("two");
 
    std::cout << "Before move, one = \"" << one.str() << '"'
              << " two = \"" << two.str() << "\"\n";
 
    *one.rdbuf() = std::move(*two.rdbuf());
 
    std::cout << "After move, one = \"" << one.str() << '"'
              << " two = \"" << two.str() << "\"\n";
}

Before move, one = "one" two = "two"
After move, one = "two" two = ""