program ccm_bcast
  use ccm_mod
  call ccm_init(myid,nodes)
  if(myid .eq. 0)x=3.14
  call ccm_bcast(x)
  write(*,*)"x=",x
  call ccm_close()
end program

program mpi_bcast
  include "mpif.h"
  call mpi_init(ierr)
  call mpi_com_size(mpi_comm_world,nodes,ierr)
  call mpi_com_rank(mpi_comm_world,myid,ierr)
  if(myid .eq. 0)x=3.14
  call mpi_bcast(x,1,mpi_real,0,mpi_comm_world)
  write(*,*)"x=",x
  call mpi_finalize(ierr)
end program

program ccm_reduce
  use ccm
  integer time_info_array(8)
  integer hour,min,sec,millisec
  integer ierr,nprocs,myid
  real local_t,gtime_min,gtime_sum,gtime_max
  call ccm_init(num_procs=nprocs)
  call date_and_time(values=time_info_array)
  hour=time_info_array(5)
  min=time_info_array(6)
  sec=time_info_array(7)
  millisec=time_info_array(8)
  local_t=(hour*60+min)*60+sec+millisec/1000.0
  gtime_sum=0.0
  call ccm_reduce(local_t,gtime_sum,"+")
  call ccm_reduce(local_t,gtime_min,"min")
  call ccm_reduce(local_t,gtime_max,"max")
  if(gtime_sum .gt. 0)then
    write(*,*)gtime_min,&
              gtime_sum/nprocs,&
              gtime_max
  endif
  call ccm_close()
end program

program mpi_reduce
  include "mpif.h"
  integer time_info_array(8)
  integer hour,min,sec,millisec
  integer ierr,nprocs,myid
  real local_t,gtime_min,gtime_sum,gtime_max
  call mpi_init(ierr)
  call mpi_com_size(mpi_comm_world,nodes,ierr)
  call mpi_com_rank(mpi_comm_world,myid,ierr)
  call date_and_time(values=time_info_array)
  hour=time_info_array(5)
  min=time_info_array(6)
  sec=time_info_array(7)
  millisec=time_info_array(8)
  local_t=(hour*60+min)*60+sec+millisec/1000.0
  gtime_sum=0.0
  call mpi_reduce(local_t,gtime_sum,1,mpi_real,&
                  mpi_sum,0,mpi_com_world,ierr)
  call mpi_reduce(local_t,gtime_min,1,mpi_real,&
                  mpi_min,0,mpi_com_world,ierr)
  call mpi_reduce(local_t,gtime_max,1,mpi_real,&
                  mpi_max,0,mpi_com_world,ierr)
  if(gtime_sum .gt. 0)then
    write(*,*)gtime_min,&
              gtime_sum/nprocs,&
              gtime_max
  endif
  call mpi_finalize(ierr)
end program

program ccm_scatter
  use ccm
  implicit none
  integer :: myid,nprocs,igot,i
  integer ,allocatable :: to_send(:)
  call ccm_init(myid,nprocs)
  allocate(to_send(0:nprocs-1))
  if(myid .eq. 1)then
    do i=0,nprocs-1
      to_send(i)=i*i
    enddo
  endif
  call ccm_scatter(to_send,igot,root=1)
  write(*,*)"for i= ",myid," igot= ",igot
  call ccm_close()
end program

program mpi_scatter
  implicit none
  include "mpif.h"
  integer :: myid,nprocs,igot,i,ierr
  integer ,allocatable :: to_send(:)
  call mpi_init(ierr)
  call mpi_com_size(mpi_comm_world,nodes,ierr)
  call mpi_com_rank(mpi_comm_world,myid,ierr)
  allocate(to_send(0:nprocs-1))
  if(myid .eq. 1)then
    do i=0,nprocs-1
         to_send(i)=i*i
    enddo
  endif
  call mpi_scatter(to_send, 1,mpi_integer,&
                   igot,1,mpi_integer,&
                   1,mpi_comm_world,ierr)

  write(*,*)"for i= ",myid," igot= ",igot
  call ccm_close()
end program

program ccm_alltoallv
    use ccm
    implicit none
    integer :: myid,nodes,igot,i,j
    integer, allocatable :: xin(:),xout(:)
    integer ,allocatable :: to_send(:),to_get(:)
    real local_time,global_time
  call mpi_init(ierr)
  call mpi_com_size(mpi_comm_world,nodes,ierr)
  call mpi_com_rank(mpi_comm_world,myid,ierr)
    allocate(to_send(0:nodes-1),to_get(0:nodes-1))
    do i=0,nodes-1
       to_send(i)=myid+i
    enddo
    allocate(xin(sum(to_send)))
    call ccm_alltoall(to_send,to_get)
    allocate(xout(sum(to_get)))
    xin=myid
    call ccm_alltoallv(xin,xout,to_send,to_get)  
    write(*,"("" i= "",i4,"" xout= "",20i3)")myid,xout
    call ccm_close()
end program
  

program mpi_alltoallv
  use ccm
  implicit none
  integer :: myid,nodes,igot,i,j
  integer, allocatable :: xin(:),xout(:)
  integer ,allocatable :: to_send(:),to_get(:)
  integer ,allocatable :: sdisp(:),rdisp(:)
  integer :: i_err
  call ccm_init(myid,nodes)
  allocate(to_send(0:nodes-1),to_get(0:nodes-1))
  allocate(sdisp(0:nodes-1),rdisp(0:nodes-1))
  do i=0,nodes-1
    to_send(i)=myid+i
  enddo
  allocate(xin(sum(to_send)))
  call mpi_alltoall(xin, 1,mpi_integer,&
                    xout,1,mpi_integer,&
                    mpi_comm_world,i_err)
  allocate(xout(sum(to_get)))
  xin=myid
  rdisp(1)=0
  do i=2,nodes
    rdisp(i)=rdisp(i-1)+to_get(i-1)
  enddo
  sdisp(1)=0
  do i=2,nodes
    sdisp(i)=sdisp(i-1)+to_send(i-1)
  enddo
  call mpi_alltoallv(xin,to_send,sdisp,mpi_integer,&
                     xout, to_get,rdisp,mpi_integer,&
                     mpi_comm_world,i_err)
  write(*,"("" i= "",i4,"" xout= "",20i3)")myid,xout
  call ccm_close()
end program
  

program ccm_checkin
  use ccm
  implicit none
  integer my_id,num_nodes,the_err
  call ccm_init(my_id,num_nodes)
!this checkin should pass ok
  call ccm_checkin(10.0,"hello",the_err)
  if(the_err .ne. 0)then
    write(*,*)"error in checkin ",the_err
  else
    write(*,*)" checkin ok"
  endif
! the next lines should cause a 
! deadlock that is detected
  if(my_id .eq. 1)then
    call ccm_checkin(10.0,"one")
  else
    call ccm_checkin(10.0,"the_rest")
  endif
  call ccm_close()
end program

Left to the student as an exercise