Apparently boost::asio::async_read
doesn't like strings, as the only overload of boost::asio::buffer
allows me to create const_buffer
s, so I'm stuck with reading everything into a streambuf.
Now I want to copy the contents of the streambuf into a string, but it apparently only supports writing to char* (sgetn()
), creating an istream with the streambuf and using getline()
.
Is there any other way to create a string with the streambufs contents without excessive copying?
I don't know whether it counts as "excessive copying", but you can use a stringstream:
std::ostringstream ss;
ss << someStreamBuf;
std::string s = ss.str();
Like, to read everything from stdin into a string, do
std::ostringstream ss;
ss << std::cin.rdbuf();
std::string s = ss.str();
Alternatively, you may also use a istreambuf_iterator
. You will have to measure whether this or the above way is faster - i don't know.
std::string s((istreambuf_iterator<char>(someStreamBuf)),
istreambuf_iterator<char>());
Note that someStreamBuf
above is meant to represent a streambuf*
, so take its address as appropriate. Also note the additional parentheses around the first argument in the last example, so that it doesn't interpret it as a function declaration returning a string and taking an iterator and another function pointer ("most vexing parse").