Re: Empty out an iostream and reuse it within a loop
On Nov 21, 3:01 am, Christopher <cp...@austin.rr.com> wrote:
On Nov 20, 8:48 pm, "Alf P. Steinbach" <al...@start.no> wrote:
* Christopher:
[...]
Yes, that leads to my next question. It seems that some of my
colleagues are obsessed with a "Do not instantiate objects within a
loop, because it is more costly to performance" rule. I disagree with
this rule very much. I understand, if an object took minutes to
constructm, but simple data types like those in the STL? This bug was
introduced by said rule, because the ostringstream was declared within
the loop previously and worked fine, then someone moved it.
I presume that that person has since been fired for
incompetence.
Is it not just as costly to call ostringstream.str("") as
constructing a new ostringstream? If not, isn't the difference
negligible?
It depends on the implementation. If there's no performance
problem, do whatever is cleanest. If there is a performance
problem, use the profiler to see where it's coming from. If it
is due to the constructor of std::ostringstream (which I doubt
is the case very often), then you might try the alternative, to
see if it helps. It might (but it's certainly not guaranteed).
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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