a question about code optimization

[龙海涛]

> Here the situation is quite simple. Because a is a template the 
> vector<int>::size() method is probably included in the header files. This 
> means that the compiler can examine or inline the code of the method. If the 
> compiler additionally determines that in /*do something*/ the size is not 

i want to know whether Gcc can determines the size is changed or not...

i did some experiment, and the result is not bad.

anyone can give me some theoritical hints?

> changed, then the optimization is quite straigthforward
> 
> Christoph