Re: Problems using std::map inside someone else code

"Alex Blekhman" <xfkt@oohay.moc>
Sun, 1 Oct 2006 19:03:31 +0200
"Angus" wrote:


I am using some socket classes - for example a
CSocketServer class. But I
want to add to the functionality so I declare a CAgents
class inside
CSocketServer like this:

class CAgents
 m_Socket = 0;
 m_dwDeviceID = 0;
}; // default constructor - init values to sensible

  CAgents(const Socket* pSocket, const DWORD DeviceID,
const std::string&
   m_Socket = pSocket;
   m_dwDeviceID = DeviceID;
   m_strLogin = strLogin;
  CAgents(const CAgents& rhs)
  {}; // assign rhs = eg

 const Socket* m_Socket; // ptr to socket for client
DWORD m_dwDeviceID; // (DeviceID) extn
std::string m_strLogin; // logon

DWORD GetDeviceID() const
return m_dwDeviceID;

std::string GetLogin() const
return m_strLogin;

const Socket* GetSocket() const
return m_Socket;

CAgents& operator=(const CAgents& rhs)
m_Socket = rhs.GetSocket();
m_dwDeviceID = rhs.GetDeviceID();
m_strLogin = rhs.GetLogin();
return *this;


I can create CAgents no problem at all. Eg:
CAgents myagent; // default constructor - just initialises
everything to
basic values
myagent.m_Socket = 0;
myagent.m_dwDeviceID = 8;
myagent.m_strLogin = "Sarah";
CAgents heragent = myagent; // operator=
CAgents thisagent(0, 3, "Angus");

But when I try to use std::map I get compilation problems.

For example,
// std::map<Key,Val>:
std::map<int, CAgents> m_AgentsList;
m_AgentsList[8] = myagent; // compile error line
SocketServer.cpp(410) : error C2678: binary '[' : no
operator defined which
takes a left-hand operand of type 'const class
CSocketServer::CAgents,struct std::less<int>,class
CSocketServer::CAgents> >' (or there is no acceptable

I don't get these compilation errors if I setup a test
program using CAgents
and std::map but NOT using CSocketServer.

What is it about the SocketServer class or classes I am
using that gives me
this headache? How can I resolve?

I already answered you in previous post that
`std::map::operator[]' cannot be used on constant map. Also,
copy constructor and assignment operator are not necessary
for your CAgents class. Compiler will generate them
automatically exactly as you wrote them. However, beware of
copying m_Socket pointer between CAgents instances. Remember
that after copying/assignment both CAgents instances will
contain the same pointer.


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