Read only desired amount of bytes using Boost.Asio

问题

I'm just creating a very simple C++ class that provides me a few methods, like connect() and read(), instead of exposing all the Boost.Asio socket calls.

Right now, I'm trying to find out how to create a method that reads only the desired amount of bytes:

SocketClient::read(int bytes, char* data); //reads desired amount of bytes and puts them in data, size of data>bytes!

Unfortunately, I found no read_byte function in Boost.Asio. I do not want to drop bytes that have been received, but not yet read.

Here is my class.

回答1:

The read function seems to provide exactly what you need:

This function is used to read a certain number of bytes of data from a stream. The call will block until one of the following conditions is true:

- The supplied buffers are full. That is, the bytes transferred
  is equal to the sum of the buffer sizes.
- An error occurred.

Example usage:

boost::asio::read(stream, boost::asio::buffer(data, size));

来源：https://stackoverflow.com/questions/15416270/read-only-desired-amount-of-bytes-using-boost-asio