bit_func.f90

program bit_functions ! GitHub FortranTip bit_func.f90
implicit none
! use 1-byte integers for illustration
integer, parameter :: ikind = selected_int_kind(1)
integer (kind=ikind) :: i, j, nbits
integer (kind=ikind), allocatable :: ivec(:)
integer, parameter   :: ni = 4
logical, allocatable :: bits(:)
nbits = bit_size(i)
allocate (bits(nbits))
ivec = [(i,i=nbits-1,0,-1)]
print "('bit representation of ',i0,'-bit integers')",nbits
print "(14x,'bit position')"
print "(9x,'i',2x,*(i3))",ivec
do i=-2,ni
   print "(i10,2x,*(i3))",i,merge(1,0,btest(i,ivec))
end do
print "(/,a,*(1x,i0))", &
  "not(1), iand(2,3), ior(2,3), ieor(2,3) =", &
   not(1), iand(2,3), ior(2,3), ieor(2,3)
end program bit_functions
! output:
! bit representation of 8-bit integers
!               bit position
!          i    7  6  5  4  3  2  1  0
!         -2    1  1  1  1  1  1  1  0
!         -1    1  1  1  1  1  1  1  1
!          0    0  0  0  0  0  0  0  0
!          1    0  0  0  0  0  0  0  1
!          2    0  0  0  0  0  0  1  0
!          3    0  0  0  0  0  0  1  1
!          4    0  0  0  0  0  1  0  0
! 
! not(1), iand(2,3), ior(2,3), ieor(2,3) = -2 2 3 1