MPI_TYPE_CREATE_STRUCT(3)			     Open MPI				 MPI_TYPE_CREATE_STRUCT(3)

MPI_Type_create_struct — Creates a structured data type.

SYNTAX
   C Syntax
	  #include <mpi.h>

	  int MPI_Type_create_struct(int count, int array_of_blocklengths[],
	       const MPI_Aint array_of_displacements[], const MPI_Datatype array_of_types[],
	       MPI_Datatype *newtype)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'
	  MPI_TYPE_CREATE_STRUCT(COUNT, ARRAY_OF_BLOCKLENGTHS,
		       ARRAY_OF_DISPLACEMENTS, ARRAY_OF_TYPES, NEWTYPE, IERROR)
	       INTEGER COUNT, ARRAY_OF_BLOCKLENGTHS(*), ARRAY_OF_TYPES(*),
	       INTEGER NEWTYPE, IERROR
	       INTEGER(KIND=MPI_ADDRESS_KIND) ARRAY_OF_DISPLACEMENTS(*)

   Fortran 2008 Syntax
	  USE mpi_f08
	  MPI_Type_create_struct(count, array_of_blocklengths,
		       array_of_displacements, array_of_types, newtype, ierror)
	       INTEGER, INTENT(IN) :: count, array_of_blocklengths(count)
	       INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) ::
	       array_of_displacements(count)
	       TYPE(MPI_Datatype), INTENT(IN) :: array_of_types(count)
	       TYPE(MPI_Datatype), INTENT(OUT) :: newtype
	       INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS
       • count:	  Number   of	blocks	 (integer)   —	 also	number	 of   entries  in  arrays  array_of_types,
	 array_of_displacements, and array_of_blocklengths.

       • array_of_blocklengths: Number of elements in each block (array of integers).

       • array_of_displacements: Byte displacement of each block (array of integers).

       • array_of_types: Type of elements in each block (array of handles to data-type objects).

OUTPUT PARAMETERS
       • newtype: New data type (handle).

       • ierror: Fortran only: Error status (integer).

DESCRIPTION
       MPI_Type_create_struct  creates	a  structured  data  type.  This  routine  replaces   MPI_Type_struct	<#
       mpi-type-struct>, which is now deprecated.

       MPI_Type_create_struct	 is    the    most    general	 type	 constructor.	It   further   generalizes
       MPI_Type_create_hindexed	 <#mpi-type-create-hindexed>  in  that	it  allows  each  block	 to   consist	of
       replications of different datatypes.

       Example 1: Let type1 have type map

	  {(double, 0), (char, 8)}

       with  extent  16. Let B = (2, 1, 3), D = (0, 16, 26), and T = (MPI_FLOAT, type1, MPI_CHAR).  Then a call to
       MPI_Type_create_struct(3, B, D, T, newtype) returns a datatype with type map

	  {
	   (float, 0), (float,4),	      // 2 float
	   (double, 16), (char, 24),	      // 1 type1
	   (char, 26), (char, 27), (char, 28) // 3 char
	  }

       That is, two copies of MPI_FLOAT starting at 0, followed by one copy of type1 starting at 16,  followed	by
       three copies of MPI_CHAR, starting at 26.

       Example 2:

       An example of a struct with only some components part of the type

	  struct MyStruct {
	      double x[2], y;
	      char a;
	      int n;
	  };

	  // create a new type where we only send x, y and n
	  int B[] = {
	      2, // 2 double's
	      1, // 1 double
	      1, // 1 int
	      1	 // alignment padding
	  };
	  MPI_Aint D[] = {
	      offsetof(struct MyStruct, x),
	      offsetof(struct MyStruct, y),
	      offsetof(struct MyStruct, n),
	      sizeof(struct MyStruct)
	  };
	  MPI_Datatype T[] = {
	      MPI_DOUBLE,
	      MPI_DOUBLE,
	      MPI_INT,
	      MPI_UB
	  };

	  MPI_Datatype mpi_dt_mystruct;
	  MPI_Type_create_struct(4, B, D, T, &mpi_dt_mystruct);
	  MPI_Type_commit(&mpi_dt_mystruct);

	  // We can now send a struct (omitting a)

	  struct MyStruct values[3];

	  if ( rank == 0 ) {
	      // ... initialize values
	      MPI_Send(values, 3, mpi_dt_mystruct, 1, 0, MPI_COMM_WORLD);
	  } else if ( rank == 1 ) {
	      MPI_Recv(values, 3, mpi_dt_mystruct, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
	  }

       For more information, see section 5.1.2 of the MPI-4.0 Standard.

NOTES
       If  an  upper  bound  is	 set  explicitly by using the MPI datatype MPI_UB, the corresponding index must be
       positive.

       The MPI-1 Standard originally made vague statements about padding and alignment; this was intended to allow
       the simple definition of structures that could be sent with a count greater than one. For example,

	  struct {int a; char b;} foo;

       may have

	  sizeof(foo) = sizeof(int) + sizeof(char);

       defining the extent of a datatype as including an epsilon, which would have allowed  an	implementation	to
       make the extent an MPI datatype for this structure equal to 2*sizeof(int). However, since different systems
       might  define  different paddings, a clarification to the standard made epsilon zero. Thus, if you define a
       structure datatype and wish to send or receive multiple items, you  should  explicitly  include	an  MPI_UB
       entry as the last member of the structure. See the above example.

ERRORS
       Almost  all MPI routines return an error value; C routines as the return result of the function and Fortran
       routines in the last argument.

       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>/MPI_Init_thread <#mpi-init-thread>,
       after MPI_Finalize <#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 <#
       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>/MPI_Comm_spawn_multiple	<#
       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 <#mpi-abort> was called on that communicator. If called
	 on  a window or file, acts as if MPI_Abort <#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	<#mpi-comm-create-errhandler>	  then	   MPI_Comm_set_errhandler	<#
	 mpi-comm-set-errhandler>

       • MPI_File_create_errhandler	 <#mpi-file-create-errhandler>	   then	    MPI_File_set_errhandler	<#
	 mpi-file-set-errhandler>

       • MPI_Session_create_errhandler	 <#mpi-session-create-errhandler>   then   MPI_Session_set_errhandler	<#
	 mpi-session-set-errhandler> or at MPI_Session_init <#mpi-session-init>

       • MPI_Win_create_errhandler	<#mpi-win-create-errhandler>	  then	    MPI_Win_set_errhandler	<#
	 mpi-win-set-errhandler>

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>.

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

       See also:

	  • MPI_Type_struct <#mpi-type-struct>

	  • MPI_Type_create_hindexed <#mpi-type-create-hindexed>

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026				 MPI_TYPE_CREATE_STRUCT(3)
