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.TH "MPI_GROUP_C2F" "3" "Sep 17, 2026" "" "Open MPI"
.INDENT 0.0
.INDENT 3.5
.UNINDENT
.UNINDENT
.sp
MPI_Comm_f2c \%<#\:mpi-comm-f2c>, MPI_Comm_c2f \%<#\:mpi-comm-c2f>, MPI_File_f2c \%<#\:mpi-file-f2c>, MPI_File_c2f \%<#\:mpi-file-c2f>, MPI_Info_f2c \%<#\:mpi-info-f2c>,
MPI_Info_c2f \%<#\:mpi-info-c2f>, MPI_Message_f2c \%<#\:mpi-message-f2c>, MPI_Message_c2f \%<#\:mpi-message-c2f>, MPI_Op_f2c \%<#\:mpi-op-f2c>, MPI_Op_c2f \%<#\:mpi-op-c2f>,
MPI_Request_f2c \%<#\:mpi-request-f2c>, MPI_Request_c2f \%<#\:mpi-request-c2f>, MPI_Type_f2c \%<#\:mpi-type-f2c>, MPI_Type_c2f \%<#\:mpi-type-c2f>,
MPI_Win_f2c \%<#\:mpi-win-f2c>, MPI_Win_c2f \%<#\:mpi-win-c2f> \- Translates a C handle into a Fortran
handle, or vice versa.
.SH SYNTAX
.SS C Syntax
.INDENT 0.0
.INDENT 3.5
.sp
.EX
#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)
.EE
.UNINDENT
.UNINDENT
.SH DESCRIPTION
.sp
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. The type definition MPI_Fint is provided in C for
an integer of the size that matches a Fortran \fIINTEGER\fP; usually,
MPI_Fint will be equivalent to \fIint\fP\&. 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.
.sp
For example, if \fIcomm\fP is a valid Fortran handle to a communicator, then
MPI_Comm_f2c \%<#\:mpi-comm-f2c> returns a valid C handle to that same communicator; if
\fIcomm\fP = MPI_COMM_NULL (Fortran value), then MPI_Comm_f2c \%<#\:mpi-comm-f2c> returns a null
C handle; if \fIcomm\fP is an invalid Fortran handle, then MPI_Comm_f2c \%<#\:mpi-comm-f2c>
returns an invalid C handle.
.SH NOTE
.sp
This function does not return an error value. Consequently, the result
of calling it before MPI_Init \%<#\:mpi-init> or after MPI_Finalize \%<#\:mpi-finalize> is undefined.
.SH Copyright
2003-2026, The Open MPI Community
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