Scala char to int conversion

问题:

def multiplyStringNumericChars(list: String): Int = {
  var product = 1;
  println(s"The actual thing  + $list")
  list.foreach(x => { println(x.toInt);
                      product = product * x.toInt;
                    });

  product;
};

This is a function that takes a String like 12345 and should return the result of 1 * 2 * 3 * 4 * 5. However, I'm getting back doesn't make any sense. What is the implicit conversion from Char to Int actually returning?

It appears to be adding 48 to all the values. If instead I do product = product * (x.toInt - 48) the results are correct.

回答1:

It does make sense: that is the way how characters encoded in ASCII table: 0 char maps to decimal 48, 1 maps to 49 and so on. So basically when you convert char to int, all you need to do is to just subtract '0':

scala> '1'.toInt
// res1: Int = 49

scala> '0'.toInt
// res2: Int = 48

scala> '1'.toInt - 48
// res3: Int = 1

scala> '1' - '0'
// res4: Int = 1

Or just use x.asDigit, as @Reimer said

scala> '1'.asDigit
// res5: Int = 1