MPI_SESSION_F2C(3)

💖 MPI_SESSION_F2C(3) — the Open MPI glow-up 💖

okay bestie, we're doing the Open MPI thing, and today's episode is about MPI_Session_c2f and MPI_Session_f2c — the two little translators that turn a C session handle into a Fortran INTEGER-style session handle, or vice versa. it's giving bilingual icon behavior, fr fr 🦋✨

---

✨ SYNOPSIS ✨

🎀 C Syntax

#include <mpi.h>

int MPI_Session_f2c(const MPI_Fint *f_session, MPI_Session *c_session)
int MPI_Session_c2f(const MPI_Session *c_session, MPI_Fint *f_session)

like, that's the whole vibe. two functions, two directions, no drama 💅

---

🌸 PARAMETERS 🌸

• f_session — the mpi-style INTEGER MPI session object. yes, it's the Fortran-flavored one, it's just built different 🧚
• c_session — the C-style MPI session object. the C one, the struct one, the one your C code is obsessed with 👑

---

💫 DESCRIPTION 💫

so here's the tea ☕ — these two procedures live in C, and their whole job is converting a Fortran session (which is literally an array of integers) into a C session (which is a structure), and also the other way around. both directions, slay.

and the conversion is not doing a half job, no cap — the conversion happens on all the information in session, including the stuff that's hidden. i'm talking zero session information lost in the conversion. it ate and left no crumbs 😭🔥

when you're using MPI_Session_f2c():

• if f_session is a valid Fortran session, then MPI_Session_f2c() returns in c_session a valid C session with the same content — bestie gets the exact same session, just in C form 💖
• if f_session is the Fortran value of MPI_SESSION_NULL, or if f_session is not a valid Fortran session, then the call is erroneous. that's the red flag 🚩 not the vibe, do not proceed.

when you're using MPI_Session_c2f(), the opposite conversion is applied. and listen: if c_session is MPI_SESSION_NULL, or if c_session is not a valid C session, then the call is erroneous. same energy, same warning, periodt 💀

fr fr, invalid or NULL handles are erroneous calls — that's straight from the source, don't try to be cute about it.

---

📝 NOTES 📝

these functions are only available in C. they are not available in any of the Fortran MPI interfaces. so if you're in Fortran land looking for them… they're not there, babe 🙈 ngnl that's just how it is.

---

👑 Copyright 👑

2003-2026, The Open MPI Community

---

and that's the whole page, bestie — originally stamped Sep 10, 2026 as MPI_SESSION_F2C(3) in the Open MPI manual. go forth and convert those handles responsibly, mwah 💜💅✨