Re: Fast means of finding a value in a vector

"Alex Blekhman" <xfkt@oohay.moc>
Sat, 30 Sep 2006 21:40:17 +0300
"Angus" wrote:

I have a struct that looks like this:

struct agents
  Socket* agentsocket; // ptr to socket for client
  DWORD dwDeviceID; // (DeviceID) extn
  char szLogon[100]; // Remedy logon

Which I populate like this:
std::vector<agents> AgentsList;
agents thisagent;
thisagent.agentsocket = whateversocket;
thisagent.dwDeviceID = 6;
lstrcpy(thisagent.szLogon, "Angus");

There might be 70 or so agents in AgentsList. I have the
dwDeviceID and
dwDeviceID is unique. What is the fastest way to find eg
the AgentsList
item where dwDeviceID = x ?

Actually, for 70 elements any find algorithm will do. I'm
not sure you will be able to measure significant differences
between various methods. However, for sake of pure elegance,
you can use std::map indeed, as you mentioned in other post.

As an exercise you can define `operator <' for `agents' type
and try to compare between std::map::find, std::find and
std::binary_search. In order to apply std::binary_search you
will need to sort `AgentsList' vector beforehand.


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