Re: extensible math functions: variable number of arguments and class templates

From:
"Alf P. Steinbach" <alfps@start.no>
Newsgroups:
comp.lang.c++
Date:
Wed, 11 Jul 2007 14:41:40 +0200
Message-ID:
<1399k06roshsm21@corp.supernews.com>
* terminator:

On Jul 10, 2:54 pm, "Alf P. Steinbach" <a...@start.no> wrote:

* terminator:

On Jul 10, 6:46 am, "Alf P. Steinbach" <a...@start.no> wrote:

Pass a vector of pairs.

or pass a pair of vectors:
#include <vector>
void do_math(const std::vector<double>& ,const std::vector<double>&);
void myfunc(){
     std::vector<double> v1,v2;
     v1[1]=someValue1;
     v1[2]=someValue2;
//and so forth
     ...
     do_math(v1,v2);
}

Perhaps you can figure out why I did not recommend that?


Please clarify your point ; I am not that sharp.


A vector of pairs guarantees that there will be pairs of values, only.
A pair of vectors offers no such guarantee: the vector sizes can be
different. This introduces an unnecessary point of failure and error
detection (with attendant complexity) in the 'do_math' function.

(Btw., I think you meant 'push_back', not assignment, above. Or else
you meant to initialize the vectors with some size. As it stands the
above code is undefined behavior.)

Cheers,

- Alf

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