Generic Operator

<<(_:_:)

Returns the result of shifting a value’s binary representation the specified number of digits to the left.

Declaration

static func << <RHS>(lhs: Int32, rhs: RHS) -> Int32 where RHS : BinaryInteger

Parameters

lhs

The value to shift.

rhs

The number of bits to shift lhs to the left.

Discussion

The << operator performs a smart shift, which defines a result for a shift of any value.

  • Using a negative value for rhs performs a right shift using abs(rhs).

  • Using a value for rhs that is greater than or equal to the bit width of lhs is an overshift, resulting in zero.

  • Using any other value for rhs performs a left shift on lhs by that amount.

The following example defines x as an instance of UInt8, an 8-bit, unsigned integer type. If you use 2 as the right-hand-side value in an operation on x, the value is shifted left by two bits.

let x: UInt8 = 30                 // 0b00011110
let y = x << 2
// y == 120                       // 0b01111000

If you use 11 as rhs, x is overshifted such that all of its bits are set to zero.

let z = x << 11
// z == 0                         // 0b00000000

Using a negative value as rhs is the same as performing a right shift with abs(rhs).

let a = x << -3
// a == 3                         // 0b00000011
let b = x >> 3
// b == 3                         // 0b00000011