ReadMsgUDP中的返回参数“ flags”是什么意思？

Question

I'm using the function ReadMsgUDP in connectionless-oriented UDP, and it goes well so far. But I have no idea about the return parameter flags, anyone knows it?

Moreover, I'm Chinese and cannot visit the official Go website in Google, can anyone send me some official documents of Go via mail?

Answer 1

You don't need to have access to Go's website to read the documentation. The distributions include a tool called godoc which can start a local HTTP server and host a similar website you see on Go's home page. You can start it locally by running the following command:

godoc -http=:6060

Then visit the following local URL in your browser:

http://localhost:6060/

Documentation of UDPConn.ReadMsgUDP():

http://localhost:6060/pkg/net/#UDPConn.ReadMsgUDP

Quoting the relevant part:

func (c *UDPConn) ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *UDPAddr, err error)

ReadMsgUDP reads a packet from c, copying the payload into b and the associated out-of-band data into oob. It returns the number of bytes copied into b, the number of bytes copied into oob, the flags that were set on the packet and the source address of the packet.