MPI_INFO_F2C(3)

🦋 NAME 🦋

okay bestie, welcome to MPI_INFO_F2C — this is the Open MPI glow-up page for the handle-translation girlies ✨

The whole squad here is:

• 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

and what do they do? literally just this: Translates a C handle into a Fortran handle, or vice versa. That's the whole job. slay 💅

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✨ 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)

not me spotting MPI Fint and MPI Group in the MPI_Group lines 💀 no shade, that's just how it's printed, so it stays. copying it exactly, periodt.

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💖 DESCRIPTION 💖

So here's the tea, bestie 🫖 — handles get passed between Fortran and C using an explicit C wrapper that converts Fortran handles into C handles. Fortran does not get direct access to C handles. nope, never, not a thing. 🙈

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. 👑

And the handle translation functions? They're provided in C, and their entire main-character arc is converting from a Fortran handle (which is an integer) to a C handle, and vice versa. that's it, that's the vibe. 🌈

fr fr, let's do an 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 (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 💀 lowkey ominous but that's the rules.

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🚨 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. undefined behaviour is NOT cute, it's NOT slay, do not do it, I am begging 🛑😭

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📜 Copyright 📜

2003-2026, The Open MPI Community

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okay that's the whole page, mwah 🎀 stay hydrated, translate those handles responsibly, and remember: it's giving Open MPI, dated Sep 10, 2026 — MPI_INFO_F2C(3), and she ate. 💜👑🦋