[Mpi-forum] MPI_Count

Jeff Squyres jsquyres at cisco.com
Mon Jan 25 15:04:57 CST 2010

On Jan 24, 2010, at 9:21 PM, Snir, Marc wrote:

> I would suggest to use explicitly 64 bit integers as the type of count in the new functions. I.e., int64_t in C and INTEGER(KIND=8) in Fortran. Both types are part of the (C/Fortran) standard.

FWIW, I mentioned the above point on the MPI3 Fortran WG mailing list and got this reply:

> Please do not touch any of the <stdint.h> stuff with a
> bargepole!  Stick to the basic types and MPI type names.
> There are many different ways where <stdint.h> integers cause portability,
> efficiency and other problems.  Inter alia, the current revision of C is
> thinking of changing them in ways that could be incompatible with old code,
> and they are semantically incompatible with Fortran and many other languages
> in several respects.
> MPI_count gives the opportunity to evade any such chaos, whether introduced
> by the standard or an implementation.

Jeff Squyres
jsquyres at cisco.com

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