# <<(_:_:) Returns the result of shifting a value’s binary representation the specified number of digits to the left. ``` static func << (lhs: Self, rhs: RHS) -> Self 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 ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)