Binary to hexadecimal in Swift

Question

I have a string in binary (for example "00100100"), and I want it in hexadecimal (like "24").

Is there a method written to convert Binary to Hexadecimal in Swift?

I'd be very surprised, but its not hard to do if you cut up the string into 4-character chunks. — Scott Hunter
– Scott Hunter, Commented Oct 23, 2014 at 13:46

Martin R · Accepted Answer · 2017-11-09 15:51:55Z

8

A possible solution:

func binToHex(bin : String) -> String {
    // binary to integer:
    let num = bin.withCString { strtoul($0, nil, 2) }
    // integer to hex:
    let hex = String(num, radix: 16, uppercase: true) // (or false)
    return hex
}

This works as long as the numbers fit into the range of UInt (32-bit or 64-bit, depending on the platform). It uses the BSD library function strtoul() which converts a string to an integer according to a given base.

For larger numbers you have to process the input in chunks. You might also add a validation of the input string.

Update for Swift 3/4: The strtoul function is no longer needed. Return nil for invalid input:

func binToHex(_ bin : String) -> String? {
    // binary to integer:
    guard let num = UInt64(bin, radix: 2) else { return nil }
    // integer to hex:
    let hex = String(num, radix: 16, uppercase: true) // (or false)
    return hex
}

edited Nov 9, 2017 at 15:51

answered Oct 23, 2014 at 13:52

Martin R

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2 Comments

Martin R Over a year ago

Thanks to the anonymous downvoter, who reminded me to update the code for the current Swift :)

Sunil Lohar Over a year ago

What if i want to convert 80 char long string to Hex e.g. "10000000000000000000000000000000000000000000000000000000000000000000000000000001" , it wont allow beyond 64bits.

XYZ · Accepted Answer · 2015-02-15 13:38:49Z

0

let binaryInteger = 0b1 
// Your binary number
let hexadecimalNum = String(binaryInteger, radix: 16) 
// convert into string format in whatever base you want

For more information

let decimalInteger = 15       // prefix NONE
let binaryInteger = 0b10001   // prefix 0b
let octalInteger = 0o21       // prefix 0o
let hexadecimalInteger = 0x11 // prefix 0x

answered Feb 15, 2015 at 13:38

XYZ

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