map<,> optimization question

[mcassiani]

Hi,



I need use map faster as possible (I store in the map data about open
network connections).



First a question, this code fragment is from "The C++ Programming........
3rd edition by B. Stroustrup"



m[k] is equivalent to (*(m.insert(make_pair(k,V()))).first)).second



The work of V() is to create a void base tape? if so, the expression:





m.insert(make_pair(k,objItem))



where objItem is my object is a better choice?



thanks

Marco C.

 

[Victor Bazarov]

I need use map faster as possible (I store in the map data about open
network connections).

First a question, this code fragment is from "The C++ Programming........
3rd edition by B. Stroustrup"

m[k] is equivalent to (*(m.insert(make_pair(k,V()))).first)).second

The work of V() is to create a void base tape? if so, the expression:
Right.

m.insert(make_pair(k,objItem))

where objItem is my object is a better choice?

Could be. You won't know until you actually put it into the working
program and run it under a profiler. Speculation costs very little and
has no real value. Get results from timing your process, then judge.

V

 

[mcassiani]

Thanks for quick reply.

 

[msalters]

Hi,

I need use map faster as possible (I store in the map data about open
network connections).

These days, memory tends to be a lot faster than I/O. Usually, the
overhead of map will be insignificant. Just make sure the objects in
the map don't perform too much I/O - i.e. cheap default ctors.

HTH,
Michiel Salters