Hostname: Difference between revisions

Using fortran 2003 C-interoperability we can call posix C function gethostname (unix system call) directly

<lang fortran>

program test_hostname

use, intrinsic :: iso_c_binding

implicit none

interface !to function: int gethostname(char *name, size_t namelen);

integer(c_int) function gethostname(name, namelen) bind(c)

use, intrinsic :: iso_c_binding, only: c_char, c_int, c_size_t

integer(c_size_t), value, intent(in) :: namelen

character(len=1,kind=c_char), dimension(namelen), intent(inout) :: name

end function gethostname

end interface

integer(c_int) :: status

integer,parameter :: HOST_NAME_MAX=255

character(kind=c_char,len=1),dimension(HOST_NAME_MAX) :: cstr_hostname

integer(c_size_t) :: lenstr

character(len=:),allocatable :: hostname

lenstr = HOST_NAME_MAX

status = gethostname(cstr_hostname, lenstr)

hostname = c_to_f_string(cstr_hostname)

write(*,*) hostname, len(hostname)

contains

! convert c_string to f_string

pure function c_to_f_string(c_string) result(f_string)

use, intrinsic :: iso_c_binding, only: c_char, c_null_char

character(kind=c_char,len=1), intent(in) :: c_string(:)

character(len=:), allocatable :: f_string

integer i, n

i = 1

do

if (c_string(i) == c_null_char) exit

i = i + 1

end do

n = i - 1 ! exclude c_null_char

allocate(character(len=n) :: f_string)

f_string = transfer(c_string(1:n), f_string)

end function c_to_f_string

end program test_hostname

</lang>