demo_system_opendir Program

     program demo_system_opendir
     use M_system, only : system_opendir,system_readdir
     use M_system, only : system_closedir
     use iso_c_binding
     implicit none
     type(c_ptr)                  :: dir
     character(len=:),allocatable :: filename
     integer                      :: ierr
     !--- open directory stream to read from
     call system_opendir('.',dir,ierr)
     if(ierr.eq.0)then
        !--- read directory stream
        do
           call system_readdir(dir,filename,ierr)
           if(filename.eq.' ')exit
           write(*,*)filename
        enddo
     endif
     !--- close directory stream
     call system_closedir(dir,ierr)
     end program demo_system_opendir