Convert between Decimal, Binary and Hexadecimal in Swift

Question

What I want to know is the most code efficient way to convert (in swift 2):

• Decimal to Binary
• Binary to Decimal
• Decimal to Hexadecimal
• Hexadecimal to Decimal
• Binary to Hexadecimal
• Hexadecimal to Binary

I already have a rudimentary and long-winded way of achieving this, but I would like to find a more efficient way.

Answer 1

Both String and Int have initializers which take a radix (base). Combining those, you can achieve all of the conversions:

// Decimal to binary let d1 = 21 let b1 = String(d1, radix: 2) print(b1) // "10101"  // Binary to decimal let b2 = "10110" let d2 = Int(b2, radix: 2)! print(d2) // 22  // Decimal to hexadecimal let d3 = 61 let h1 = String(d3, radix: 16) print(h1) // "3d"  // Hexadecimal to decimal let h2 = "a3" let d4 = Int(h2, radix: 16)! print(d4) // 163  // Binary to hexadecimal let b3 = "10101011" let h3 = String(Int(b3, radix: 2)!, radix: 16) print(h3) // "ab"  // Hexadecimal to binary let h4 = "face" let b4 = String(Int(h4, radix: 16)!, radix: 2) print(b4) // "1111101011001110" 

Answer 2

Swift Converter 2, 8, 10, 16

A bunch of Int and String is used to convert different systems.

Int is used for working with decimal
String is used for other types

It is safe to convert a string representation of system to decimal and decimal to string representation

String -> Int -> String 

There are samples of

binary(2) - 0b octal(8) - 0o decimal(10) hexadecimal(16) - 0x 

extension Int {          //From Decimal     //10 -> 2     func decToBinString() -> String {         let result = createString(radix: 2)         return result     }          //10 -> 8     func decToOctString() -> String { //        let result = decToOctStringFormat()         let result = createString(radix: 8)                  return result     }          //10 -> 16     func decToHexString() -> String { //        let result = decToHexStringFormat()         let result = createString(radix: 16)         return result     }          //10 -> 8     func decToOctStringFormat(minLength: Int = 0) -> String {          return createString(minLength: minLength, system: "O")     }      //10 -> 16     func decToHexStringFormat(minLength: Int = 0) -> String {          return createString(minLength: minLength, system: "X")     }          fileprivate  func createString(radix: Int) -> String {         return String(self, radix: radix, uppercase: true)     }          fileprivate func createString(minLength: Int = 0, system: String) -> String {         //0 - fill empty space by 0         //minLength - min count of chars         //system - system number         return String(format:"%0\(minLength)\(system)", self)     } } 

extension String {          //To Decimal     //2 -> 10     func binToDec() -> Int {         return createInt(radix: 2)     }          //8 -> 10     func octToDec() -> Int {         return createInt(radix: 8)     }          //16 -> 10     func hexToDec() -> Int {         return createInt(radix: 16)     }          //Others     //2 -> 8     func binToOct() -> String {         return self.binToDec().decToOctString()     }          //2 -> 16     func binToHex() -> String {         return self.binToDec().decToHexString()     }          //8 -> 16     func octToHex() -> String {         return self.octToDec().decToHexString()     }          //16 -> 8     func hexToOct() -> String {         return self.hexToDec().decToOctString()     }          //16 -> 2     func hexToBin() -> String {         return self.hexToDec().decToBinString()     }          //8 -> 2     func octToBin() -> String {         return self.octToDec().decToBinString()     }      //Additional     //16 -> 2     func hexToBinStringFormat(minLength: Int = 0) -> String {                  return hexToBin().pad(minLength: minLength)     }          fileprivate func pad(minLength: Int) -> String {         let padCount = minLength - self.count                  guard padCount > 0 else {             return self         }          return String(repeating: "0", count: padCount) + self     }       fileprivate func createInt(radix: Int) -> Int {         return Int(self, radix: radix)!     }      } 

Tests:

func testConverter() {     let decInt = 13511     let binStr = "11010011000111"     let octStr = "32307"     let hexStr = "34C7"          //From Decimal     //10 -> 2     XCTAssertEqual(binStr, decInt.decToBinString())     //10 -> 8     XCTAssertEqual(octStr, decInt.decToOctString())     //10 -> 16     XCTAssertEqual(hexStr, decInt.decToHexString())          //To Decimal     //2 -> 10     XCTAssertEqual(decInt, binStr.binToDec())     //8 -> 10     XCTAssertEqual(decInt, octStr.octToDec())     //16 -> 10     XCTAssertEqual(decInt, hexStr.hexToDec())          //Others     //2 -> 8     XCTAssertEqual(octStr, binStr.binToOct())     //2 -> 16     XCTAssertEqual(hexStr, binStr.binToHex())     //8 -> 16     XCTAssertEqual(hexStr, octStr.octToHex())     //16 -> 8     XCTAssertEqual(octStr, hexStr.hexToOct())     //16 -> 2     XCTAssertEqual(binStr, hexStr.hexToBin())     //8 -> 2     XCTAssertEqual(binStr, octStr.octToBin())      //String format feature     //10 -> 8     XCTAssertEqual("017", (15).decToOctStringFormat(minLength: 3))     //10 -> 16     XCTAssertEqual("00F", (15).decToHexStringFormat(minLength: 3))     //16 -> 2     XCTAssertEqual("0011010011000111", hexStr.hexToBinStringFormat(minLength: 16))      }