CODEWITHSUNDEEP
scala
rsan
rsan

Reputation: 1887

Hex String to Int,Short and Long in Scala

Just can't find a way to transform an Hex String to a number (Int, Long, Short) in Scala.

Is there something like "A".toInt(base)?

Upvotes: 37

Views: 37164

Answers (5)

7zark7
7zark7

Reputation: 10135

You can use the Java libs:

val number = Integer.parseInt("FFFF", 16)
> number: Int = 65535

Or if you are feeling sparky :-):

implicit def hex2int (hex: String): Int = Integer.parseInt(hex, 16)

val number: Int = "CAFE" // <- behold the magic
number: Int = 51966

Also, if you aren't specifically trying to parse a String parameter into hex, note that Scala directly supports hexadecimal Integer literals. In this case:

val x = 0xCAFE
> x: Int = 51966

Isn't Scala wonderful? :-)

Upvotes: 54

oseiskar
oseiskar

Reputation: 3372

For Long and Short, it is also possible to use the Java methods directly like

Long2long(java.lang.Long.valueOf(hexString, 16))

where Long2long can be even be omitted in some cases.

Upvotes: 5

Andrew E
Andrew E

Reputation: 8317

Anyone wanting to convert a UUID from hex to a decimal number can borrow from Benoit's answer and use BigDecimal for the job:

scala> "03cedf84011dd11e38ff0800200c9a66".toList.map(
 |   "0123456789abcdef".indexOf(_)).map(
 |     BigInt(_)).reduceLeft( _ * 16 + _)
res0: scala.math.BigInt = 5061830576017519706280227473241971302

Or more generally:

def hex2dec(hex: String): BigInt = {
  hex.toLowerCase().toList.map(
    "0123456789abcdef".indexOf(_)).map(
    BigInt(_)).reduceLeft( _ * 16 + _)
}

def uuid2dec(uuid: UUID): BigInt = {
  hex2dec(uuid.toString.replace("-",""))
}

Then:

scala> import java.util.UUID

scala> val id = UUID.fromString("3CEDF84-011D-D11E-38FF-D0800200C9A66")
id: java.util.UUID = 03cedf84-011d-d11e-38ff-0800200c9a66

scala> uuid2dec(id)
res2: BigInt = 5061830576017519706280227473241971302

One practical application for this is encoding the UUID in a barcode, where Code128 produces a shorter barcode for all digits than it does with alphanumeric strings. See notes about subtype "128A" on http://en.wikipedia.org/wiki/Code128#Subtypes.

Upvotes: 7

Benny
Benny

Reputation: 4321

What about a one-liner?

def hexToInt(s: String): Int = {
    s.toList.map("0123456789abcdef".indexOf(_)).reduceLeft(_ * 16 + _)
}

scala> hexToInt("cafe")
res0: Int = 51966

And to answer your second item:

Is there something like "A".toInt(base)?

Yes, still as a one-liner:

def baseToInt(s: String, base: String): Int = {
    s.toList.map(base.indexOf(_)).reduceLeft(_ * base.length + _)
}

scala> baseToInt("1100", "01")
res1: Int = 12

Upvotes: 12

Sergey Passichenko
Sergey Passichenko

Reputation: 6920

7zark7 answer is correct, but I want to make some additions. Implicit from String to Int can be dangerous. Instead you can use implicit conversion to wrapper and call parsing explicitly:

class HexString(val s: String) {
    def hex = Integer.parseInt(s, 16)
}
implicit def str2hex(str: String): HexString = new HexString(str)

val num: Int = "CAFE".hex

Upvotes: 31

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