Data update

Task/Twos-complement/Ada/twos-complement.ada

@@ -0,0 +1,10 @@
+with Ada.Text_IO;
+
+procedure Twos_Complement is
+   type Number is mod 2 ** 32;
+   A : constant Number := 42;
+   B : constant Number := not A + 1;
+   Is_Negative : constant Boolean := A + B = 0;
+begin
+   Ada.Text_IO.Put_Line ("B = -A is " & Is_Negative'Image);
+end Twos_Complement;

Task/Twos-complement/Fortran/twos-complement.f

@@ -0,0 +1,57 @@
+!
+program twos_complement_demo
+  implicit none
+
+  integer :: x, tc
+  integer :: nbits
+  character(len=:), allocatable :: bits_x, bits_not, bits_tc
+
+  ! Prompt for input
+  write(*,"(a)",advance="no")  "Enter a positive integer (or any integer):"
+  read  *, x
+
+  ! Determine bit-width and convert to bit-strings
+  nbits    = bit_size(x)
+  bits_x   = to_bitstring(x)
+  bits_not = to_bitstring(not(x))
+
+  ! Compute two's complement: flip all bits then add one
+  tc       = not(x) + 1
+  bits_tc  = to_bitstring(tc)
+
+  ! Display results
+  10 format(a,t30,i0)
+  20 format(a,i0,a,t30,a,/)
+  30 format(a,t30,a)
+  write(*,*)
+  write(*,10)  "Original integer:", x
+  write(*,20)  "Bit pattern (", nbits, " bits):", trim(bits_x)
+  write(*,30)  "After bitwise NOT:        ", trim(bits_not)
+  write(*,30)  "Then add 1 --> two’s comp:", trim(bits_tc)
+  write(*,*)
+  write(*,10)  "Two’s complement (decimal):", tc
+
+contains
+
+  !------------------------------------------------------------
+  ! Convert an integer to a string of ‘0’ and ‘1’
+  !------------------------------------------------------------
+  function to_bitstring(val) result(str)
+    integer, intent(in)            :: val
+    character(len=:), allocatable  :: str
+    integer                        :: n, i
+
+    ! Number of bits in this integer kind
+    n = bit_size(val)
+    allocate(character(len=n) :: str)
+
+    do i = 1, n
+      if (btest(val, n - i)) then
+        str(i:i) = '1'
+      else
+        str(i:i) = '0'
+      end if
+    end do
+  end function to_bitstring
+
+end program twos_complement_demo