Re: [Boost-users] Is it ok to pass &my_boost_array_variable[2] into a C function expecting a Type*

Subject: Re: [Boost-users] Is it ok to pass &my_boost_array_variable[2] into a C function expecting a Type*
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2012-11-29 11:41:36

AMDG

On 11/29/2012 01:47 AM, Anton Daneyko wrote:
> Hi,
> I have a two variables:
> boost::array my_boost_array_variable_1<float, 3>;
> boost::array my_boost_array_variable_2<float, 3>;
> 
> now I want to call a C function with the following signature:
> int MPI_Allreduce ( void *sendbuf, void *recvbuf, ...);
> 
> I want to pass the address of a particular element of my
> my_boost_array_variable_1 and  my_boost_array_variable_2 as a first
> and second parameter of MPI_Allreduce:
>  MPI_Allreduce(&my_boost_array_variable_1[2],
>                        &my_boost_array_variable_2[2], ...
> 

Yes, this is legal.  A pointer is a pointer,
regardless of how you get it and all of the
intermediate expressions are legal too.

> or should I rather do:
>  MPI_Allreduce(my_boost_array_variable_1.c_array() + 2,
>                        my_boost_array_variable_2.c_array() + 2, ...
> 

In Christ,
Steven Watanabe