# init(_:) Creates a new instance from the given integer. ``` init(_ source: T) where T : BinaryInteger ``` ## Parameters `source` A value to convert to this type of integer. The value passed as `source` must be representable in this type. ## Discussion Use this initializer to convert from another integer type when you know the value is within the bounds of this type. Passing a value that can’t be represented in this type results in a runtime error. In the following example, the constant `y` is successfully created from `x`, an `Int` instance with a value of `100`. Because the `Int8` type can represent `127` at maximum, the attempt to create `z` with a value of `1000` results in a runtime error. ``` let x = 100 let y = Int8(x) // y == 100 let z = Int8(x * 10) // Error: Not enough bits to represent the given value ``` --- 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)