Re: std::map compilation error

From:

"Duane Hebert" <spoo@flarn2.com>

Newsgroups:

microsoft.public.vc.stl

Date:

Sat, 30 Sep 2006 21:15:06 -0400

Message-ID:

<OquIFcP5GHA.4536@TK2MSFTNGP06.phx.gbl>

"Angus" <nospam@gmail.com> wrote in message
news:OeNHhjO5GHA.400@TK2MSFTNGP02.phx.gbl...

I have this:
struct agents
{
Socket* agentsocket; // ptr to socket for client
DWORD dwDeviceID; // DeviceID
char szLogon[100]; // logon
};
// std::vector<agents> m_AgentsList;
std::map<long, agents> m_AgentsList;

Then for example I do a find like this:
long mydevice = 4;
std::map<long, agents>::iterator i = m_AgentsList.find(mydevice);
I then get this error on line with find as above.

error C2440: 'initializing' :

cannot convert from

'class std::_Tree<long,struct std::pair<long const ,struct
CSocketServer::agents>,struct std::map<long,struct
CSocketServer::agents,struct std::less<long>,class std::allocator<struct
CSocketServer::agents> >::_Kfn,struct std::less<long>,class
std::allocator<struct CSocketServer::agents> >::const_iterator'

to

'class std::_Tree<long,struct std::pair<long const ,struct
CSocketServer::agents>,struct std::map<long,struct
CSocketServer::agents,struct std::less<long>,class std::allocator<struct
CSocketServer::agents> >::_Kfn,struct std::less<long>,class
std::allocator<struct CSocketServer::agents> >::iterator'

No constructor could take the source type, or constructor overload
resolution was ambiguous
Error executing cl.exe.

Why?

It looks like the difference is in the last line above where it says
that it can't convert from a const_iterator to and iterator.

What if you use:
std::map<long, agents>::const_iterator i = m_AgentsList.find(mydevice);

Also, be sure to check the result of find() against end() before
trying to use it.

HTH

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