MPI_TYPE_STRUCT(3)

🌸 NAME 🌸

okay so bestie, you just opened the MPI_TYPE_STRUCT(3) page from the Open MPI manual, and it's giving "legacy MPI but make it cute." MPI_Type_struct — Creates a struct data type — this routine is deprecated in favor of MPI_Type_create_struct. no cap, the manual says it right there. 💅

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✨ SYNTAX ✨

💻 C Syntax 💻

          #include <mpi.h>

          int MPI_Type_struct(int count, int *array_of_blocklengths,
               MPI_Aint *array_of_displacements, MPI_Datatype *array_of_types,
               MPI_Datatype *newtype)

🧚 Fortran Syntax 🧚

          USE MPI
          ! or the older form: INCLUDE 'mpif.h'

          MPI_TYPE_STRUCT(COUNT, ARRAY_OF_BLOCKLENGTHS,
                       ARRAY_OF_DISPLACEMENTS, ARRAY_OF_TYPES,
                       NEWTYPE, IERROR)
               INTEGER COUNT, ARRAY_OF_BLOCKLENGTHS(*)
               INTEGER ARRAY_OF_DISPLACEMENTS(*)
               INTEGER ARRAY_OF_TYPES(*), NEWTYPE, IERROR

📥 INPUT PARAMETERS 📥

• count — Number of blocks (integer) also number of entries in arrays array_of_types, array_of_displacements, and array_of_blocklengths. so it's the headcount for all three arrays, periodt.
• array_of_blocklengths — Number of elements in each block (array).
• array_of_displacements — Byte displacement of each block (array).
• array_of_types — Type of elements in each block (array of handles to datatype objects). handles, not vibes — got it.

📤 OUTPUT PARAMETERS 📤

• newtype — New datatype (handle).
• ierror — Fortran only: Error status (integer).

🌈 DESCRIPTION 🌈

deprecation alert: use of this routine is deprecated as of MPI-2. For details of use, see MPI_Type_create_struct. the manual is literally pointing you at the newer routine, iykyk. 💅

💀 ERRORS 💀

Almost all MPI routines return an error value. C routines return it as the return result of the function, and Fortran routines return it in the last argument. that's the standard MPI error-return vibe.

Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI_COMM_SELF and will call the associated MPI error handler. When MPI_COMM_SELF is not initialized (i.e., before MPI_Init/MPI_Init_thread, after MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info key to MPI_Comm_spawn/MPI_Comm_spawn_multiple. If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is called for all other MPI functions.

Open MPI includes three predefined error handlers that can be used:

• MPI_ERRORS_ARE_FATAL — Causes the program to abort all connected MPI processes.
• MPI_ERRORS_ABORT — An error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI_Abort was called on that communicator. If called on a window or file, acts as if MPI_Abort was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process.
• MPI_ERRORS_RETURN — Returns an error code to the application.

MPI applications can also implement their own error handlers by calling:

• MPI_Comm_create_errhandler then MPI_Comm_set_errhandler
• MPI_File_create_errhandler then MPI_File_set_errhandler
• MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init
• MPI_Win_create_errhandler then MPI_Win_set_errhandler

Note that MPI does not guarantee that an MPI program can continue past an error. fr fr, that's a real caveat.

See the MPI man page for a full list of MPI error codes.

See the Error Handling section of the MPI-3.1 standard for more information.

👀 SEE ALSO 👀

• MPI_Type_create_struct
• MPI_Type_create_hindexed

© COPYRIGHT ©

2003-2026, The Open MPI Community

okay bestie, that's the whole page. signing off from the Open MPI manual, dated Sep 11, 2026 — now go forth and be iconic with your struct datatypes 💅✨🍓