---
title: "init(_:radix:)"
framework: swift
role: symbol
role_heading: Initializer
path: "swift/uint64/init(_:radix:)"
---

# init(_:radix:)

Creates a new integer value from the given string and radix.

## Declaration

```swift
init?<S>(_ text: S, radix: Int = 10) where S : StringProtocol
```

## Parameters

- `text`: The ASCII representation of a number in the radix passed as radix.
- `radix`: The radix, or base, to use for converting text to an integer value. radix must be in the range 2...36. The default is 10.

## Discussion

Discussion The string passed as text may begin with a plus or minus sign character (+ or -), followed by one or more numeric digits (0-9) or letters (a-z or A-Z). Parsing of the string is case insensitive. let x = Int("123") // x == 123

let y = Int("-123", radix: 8) // y == -83 let y = Int("+123", radix: 8) // y == +83

let z = Int("07b", radix: 16) // z == 123 If text is in an invalid format or contains characters that are out of bounds for the given radix, or if the value it denotes in the given radix is not representable, the result is nil. For example, the following conversions result in nil: Int(" 100")                       // Includes whitespace Int("21-50")                      // Invalid format Int("ff6600")                     // Characters out of bounds Int("zzzzzzzzzzzzz", radix: 36)   // Out of range