xor

xor (boolean a, boolean b) ⇒ boolean

Returns the exclusive-or (XOR) on two boolean values. i.e. !($a && $b) && ($a || $b).

Notes

XOR (⊕) is based on the logic that is provided by underlying logic gates made of transistors. As such, XOR is true if and only if one condition is true. The truth table for OR and XOR is shown below:

Using XOR to construct a 1 bit adder

function adder($a, $b, $c)

  $sum = xor(xor($a, $b), $c)
  $carry = (xor($a, $b) and $c) or ($a and $b)

  return ["result" => $sum, "carry" => $carry]
end function

function main()

  print(adder(1, 0, 0))
  print(adder(0, 0, 1))
  print(adder(1, 1, 0))

end function

For more on adders, visit this page.