Stores the result of shifting a value’s binary representation the specified number of digits to the right in the left-hand-side variable.
SDK
- Xcode 9.0+
Framework
- Swift Standard Library
Declaration
static func >>= <Other>(lhs: inout Int, rhs: Other) where Other : BinaryParameters
lhsThe value to shift.
rhsThe number of bits to shift
lhsto the right.
Discussion
The >>= operator performs a smart shift, which defines a result for a shift of any value.
Using a negative value for
rhsperforms a left shift usingabs(rhs).Using a value for
rhsthat is greater than or equal to the bit width oflhsis an overshift. An overshift results in-1for a negative value oflhsor0for a nonnegative value.Using any other value for
rhsperforms a right shift onlhsby 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 right by two bits.
var x: UInt8 = 30 // 0b00011110
x >>= 2
// x == 7 // 0b00000111
If you use 11 as rhs, x is overshifted such that all of its bits are set to zero.
var y: UInt8 = 30 // 0b00011110
y >>= 11
// y == 0 // 0b00000000
Using a negative value as rhs is the same as performing a left shift using abs(rhs).
var a: UInt8 = 30 // 0b00011110
a >>= -3
// a == 240 // 0b11110000
var b: UInt8 = 30 // 0b00011110
b <<= 3
// b == 240 // 0b11110000
Right shift operations on negative values “fill in” the high bits with ones instead of zeros.
var q: Int8 = -30 // 0b11100010
q >>= 2
// q == -8 // 0b11111000
var r: Int8 = -30 // 0b11100010
r >>= 11
// r == -1 // 0b11111111