MPI_WIN_F2C(3)

💖 MPI_WIN_F2C(3) 💖

okay so welcome to the Open MPI manual, bestie — this page is the whole bestie-fied guide to the handle translators. It's giving "C and Fortran need to talk" and honestly? iconic. 💅

🌸 NAME 🌸

MPI_Comm_f2c, MPI_Comm_c2f, MPI_File_f2c, MPI_File_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 — these translate a C handle into a Fortran handle, or vice versa. fr fr. 🦋

🌈 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 ✨

Bestie, here's the tea: handles do not just vibe-hop between Fortran and C by themselves. They get passed between them by using an explicit C wrapper that converts Fortran handles into C handles. There is literally no direct access to C handles in Fortran — none, don't try it. 😭

MPI_Fint is provided in C, and its whole job is to be 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 so you can convert from a Fortran handle (which is an integer) to a C handle, and vice versa. periodt.

Example time, because we love a concrete demo: 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 (the Fortran value), then MPI_Comm_f2c returns a null C handle. And if comm is an invalid Fortran handle, then MPI_Comm_f2c returns an invalid C handle. That's the whole vibe check. ✨

🚨 NOTE 🚨

🚨 no cap: this function does not return an error value. So calling it before MPI_Init or after MPI_Finalize? The result is undefined. literally undefined. Do not collect $200. 💀

©️ COPYRIGHT ©️

2003-2026, The Open MPI Community

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okay bye bestie 🫶 — source/version: Open MPI, date: Sep 11, 2026, and the page title is MPI_WIN_F2C(3). mwah 💋