Is There an Easy Way to Convert a Boolean to an Integer?

问题

I am new to scala and I am finding the need to convert a boolean value to an integer. I know i can use something like if (x) 1 else 0 but I would like to know if there is a preferred method, or something built into the framework (ie toInt())

回答1:

If you want to mix Boolean and Int operation use an implicit as above but without creating a class:

implicit def bool2int(b:Boolean) = if (b) 1 else 0

scala> false:Int
res4: Int = 0

scala> true:Int
res5: Int = 1

scala> val b=true
b: Boolean = true


scala> 2*b+1
res2: Int = 3

回答2:

You can do this easily with implicit conversions:

class asInt(b: Boolean) {
  def toInt = if(b) 1 else 0
}

implicit def convertBooleanToInt(b: Boolean) = new asInt(b)

Then, you will get something like

scala> false toInt
res1: Int = 0

回答3:

While using an implicit is probably the best way to go, if you want a quick-and-dirty conversion from boolean to int you can use boolean.compare(false)

回答4:

Actually, I'd expect it to be if (x) 1 else 0, not if (x) 0 else 1.

That's why you should write your own conversions. Integer isn't a boolean, and if you want for some reason to store booleans as integers, then you should hone your own standards of how the truth and not truth are represented.

Boolean "true" is not a number, it is an instance of the Boolean type. Like java.lang.Boolean.TRUE. It can be stored internally as an integer, but that is an implementation detail that shouldn't be leaked into the language.

I'd say that if (x) 0 else 1 is the preferred method of conversion. It is simple and fast.

You can also write x match {case true => 0; case false => 1} if you want to use a more general pattern matching approach.

回答5:

If you don't want to go the implicit way, this may be useful:

var myBool:Boolean = true
myBool: Boolean = true

myBool.compare(false)
res3: Int = 1

myBool = false
myBool: Boolean = false

myBool.compare(false)
res3: Int = 0

回答6:

Since Scala 2.10 the solution by Jackson Davis is more often written using an implicit value class:

implicit class BoolToInt(val b:Boolean) extends AnyVal {
  def toInt = if (b) 1 else 0
  def * (x:Int) = if (b) x else 0
}

For added comfort I have also added a multiplication operator, as this is the most common use of a Boolean to Int conversion for me. I prefer this over making the conversion itself implicit (solution provided by Patrick), as that loses more of the type control than I want.

来源：https://stackoverflow.com/questions/2633719/is-there-an-easy-way-to-convert-a-boolean-to-an-integer

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scala

casting

integer

boolean