c++ - how to know that no data available on boost::asio::ip::tcp::iostream? -

i'm using boost::asio::ip::tcp::iostream read binary data tcp stream. that:

stream.read(reinterpret_cast<char*>(&packetsize), 4); // first 4 bytes length stream.read(buffer, packetsize); 

should check stream.gcount() , when next stream.gcount() == 0 means no data more available reading (tcp session finished)?

the stream members looking buried in base class http://en.cppreference.com/w/cpp/io/basic_ios

use good() , !eof() see if got data. can set flags on stream object ( exception() ) instruct stream throw exceptions in case, error occurred. makes handling times easier.