MPI_OP_C2F(3)

📦
version 5.0.11 · 14 versions
, in arch rolling

💖 NAME 💖

okay so bestie, this is MPI_OP_C2F(3) from the Open MPI manual, and it's literally the handle-translation friend group: it translates a C handle into a Fortran handle, or vice versa. no cap. 🫶

The whole cast, no skips:

  • MPI_Comm_f2c
  • MPI_Comm_c2f
  • MPI_File_f2c
  • MPI_File_c2f
  • MPI_Group_f2c
  • MPI_Group_c2f
  • MPI_Info_f2c
  • MPI_Info_c2f
  • MPI_Message_f2c
  • MPI_Message_c2f
  • MPI_Op_f2c
  • MPI_Op_c2f
  • MPI_Request_f2c
  • MPI_Request_c2f
  • MPI_Type_f2c
  • MPI_Type_c2f
  • MPI_Win_f2c
  • MPI_Win_c2f

✨ SYNTAX ✨

🌸 C Syntax

#include <mpi.h>

MPI_Comm MPI_Comm_f2c(MPI_Fint comm)
MPI_Fint MPI_Comm_c2f(MPI_Comm comm)

MPI_File MPI_File_f2c(MPI_Fint file)
MPI_Fint MPI_File_c2f(MPI_File file)

MPI_Group MPI_Group_f2c(MPI Fint group)
MPI_Fint MPI_Group_c2f(MPI Group group)

MPI_Info MPI_Info_f2c(MPI_Fint info)
MPI_Fint MPI_Info_c2f(MPI_Info info)

MPI_Message MPI_Message_f2c(MPI_Fint message)
MPI_Fint MPI_Message_c2f(MPI_Message message)

MPI_Op MPI_Op_f2c(MPI_Fint op)
MPI_Fint MPI_Op_c2f(MPI_Op op)

MPI_Request MPI_Request_f2c(MPI_Fint request)
MPI_Fint MPI_Request_c2f(MPI_Request request)

MPI_Datatype MPI_Type_f2c(MPI_Fint datatype)
MPI_Fint MPI_Type_c2f(MPI_Datatype datatype)

MPI_Win MPI_Win_f2c(MPI_Fint win)
MPI_Fint MPI_Win_c2f(MPI_Win win)

🫶 DESCRIPTION 🫶

okay so here's the tea: handles are passed between Fortran and C by using an explicit C wrapper to convert Fortran handles to C handles. There is no direct access to C handles in Fortran, periodt. 💅

The type definition MPI_Fint is provided in C for an integer of the size that matches a Fortran INTEGER; usually, MPI_Fint will be equivalent to int. The handle translation functions are provided in C to convert from a Fortran handle (which is an integer) to a C handle, and vice versa. iykyk. ✨

For example, if comm is a valid Fortran handle to a communicator, then MPI_Comm_f2c returns a valid C handle to that same communicator; if comm = MPI_COMM_NULL (Fortran value), then MPI_Comm_f2c returns a null C handle; if comm is an invalid Fortran handle, then MPI_Comm_f2c returns an invalid C handle. literally the whole f2c/c2f pipeline, and it ate. 🔥

💀 NOTE 💀

bestie, listen: this function does not return an error value. Consequently, the result of calling it before MPI_Init or after MPI_Finalize is undefined. that's the danger zone, fr fr. 😭

2003-2026, The Open MPI Community

💌 cute sign-off: this MPI_OP_C2F(3) page is from Open MPI, © 2003-2026, The Open MPI Community, dated Sep 11, 2026. byeee, go translate those handles 💅✨

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