Scala char 到 int 的转换 [英] Scala char to int conversion

问题描述

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;
};

这是一个函数，它接受一个类似于 12345 的字符串，并且应该返回 1 * 2 * 3 * 4 * 5 的结果.然而，我回来没有任何意义.从 Char 到 Int 的隐式转换实际上返回了什么?

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?

它似乎将 48 添加到所有值.如果我改为 product = product * (x.toInt - 48) 结果是正确的.

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

推荐答案

它确实有道理:这就是字符编码的方式ASCII 表:0 字符映射到十进制 48，1 映射到 49，依此类推.所以基本上当你将char转换为int时，你需要做的就是减去'0':

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

或者只是使用 x.asDigit，正如@Reimer 所说

Or just use x.asDigit, as @Reimer said

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

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