Fortran 2003

1 files changed, 57 insertions, 0 deletions

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+! SYNOPSIS:
+!
+! # gfortran -o gcd-f gcd.f03
+! # ./gcd-f 11 22 33 121
+!
+
+program GCD
+implicit none
+
+integer, allocatable :: ns(:)
+integer :: i, n
+character*20 :: tmpstr
+
+n = command_argument_count()
+
+allocate(ns(n)) ! allocate memory for numbers given in command line
+
+do i = 1, n
+    call get_command_argument(i, tmpstr)
+    ns(i) = str2int(tmpstr)
+end do
+
+print *,  gcdn(ns)
+
+deallocate(ns)
+
+
+! If we declare functions first,
+! we have to specify its types within
+! the `program' section.
+! See http://en.wikibooks.org/wiki/Fortran/Fortran_procedures_and_functions
+contains
+
+pure integer function str2int (s)
+    character*(*), intent(in) :: s
+    read (s, *) str2int
+end function
+
+pure recursive integer function gcd2 (a, b) result(GCD)
+    integer, intent(in) :: a, b
+    if (b == 0) then
+        GCD = a
+    else
+        GCD = gcd2(b, mod(a, b))
+    end if
+end function gcd2
+
+pure integer function gcdn(n)
+    integer, intent(in) :: n(:) ! n is an array
+    integer :: i
+    gcdn = n(1)
+    do i = 2, size(n)
+        gcdn = gcd2(gcdn, n(i))
+    end do
+end function
+
+end program