Re: [Boost-users] shared_lock ( ) causes Segmentation Fault in CentOS 5.5 x64?

Subject: Re: [Boost-users] shared_lock ( ) causes Segmentation Fault in CentOS 5.5 x64?
From: Zap (zippo.fire_at_[hidden])
Date: 2011-03-17 10:48:37

Frank Mori Hess <frank.hess <at> nist.gov> writes:
> 
> operator[] on maps can modify the map.  Maybe you want to use find() instead?
> 

Hi Frank,

I'll try it later, thanks for your answer,

Is there any difference of performance between 
using operator[] and .find()?

especially in frequently finding key/value of pair<string, string> in 
boost::unordered_map<pair<string, string>, boost::unordered_set<int> >.

and another question is,
could I use container in container such as what I 
wrote(unordered_set as value in unorder_map)?
is this kind of structur undefine-behaviour or it's acceptable?

if it's acceptable, did this kind of structure will cause decrasing of
performance or won't?
if it will, what kind of instead structure could I use to satisfy 
what I need to do?

Thank you