Questions about the member of the structure.

The code below is a part of the select-server.cpp from the www.tangentsoft.net/wskfaq. I don't understand what is this line
'Connection(SOCKET sd_) : sd(sd_), nCharsInBuffer(0) { }' in the Connection structure.


struct Connection {
SOCKET sd;
char acBuffer[kBufferSize];
int nCharsInBuffer;

Connection(SOCKET sd_) : sd(sd_), nCharsInBuffer(0) { } // What is this?
};
typedef vector<Connection> ConnectionList;

ConnectionList gConnections;

It's a constructor - a struct in c++ can have functions too. The constructor here is initialising the sd member with the parameter passed to it, and initialising the nCharsinBuffer member with zero.