Swift - Bitwise XOR and assignment operator

The Bitwise XOR and assignment operator (^=) assigns the first operand a value equal to the result of Bitwise XOR operation of two operands.

(x ^= y) is equivalent to (x = x ^ y)

The Bitwise XOR operator (^) is a binary operator which takes two bit patterns of equal length and performs the logical exclusive OR operation on each pair of corresponding bits. It returns 1 if only one of the bits is 1, else returns 0.

The example below describes how bitwise XOR operator works:

50 ^ 25 returns 43

     50    ->    110010  (In Binary)
   ^ 25    ->  ^ 011001  (In Binary)
    ----        --------
     43    <-    101011  (In Binary)  

The code of using Bitwise XOR and assignment operator (^=) is given below:

var x = 50
var y = 25

//Bitwise XOR and assignment operation
x ^= y

//Displaying the result
print("x = \(x)")

The output of the above code will be:

x = 43

Example: Swap two numbers without using temporary variable

The bitwise XOR and assignment operator can be used to swap the value of two variables. Consider the example below.

func swap(_ x: inout Int, _ y: inout Int) {
  print("Before Swap:")
  print("x = \(x)")
  print("y = \(y)")

  //Swap technique
  x ^= y
  y ^= x
  x ^= y

  print("\nAfter Swap:")
  print("x = \(x)")
  print("y = \(y)")
}

var a = 10
var b = 25
swap(&a, &b)

The above code will give the following output:

Before Swap:
x = 10
y = 25

After Swap:
x = 25
y = 10