如何用scala写一个计算机

作为AI语言模型，我可以为您提供一个scala计算器的示例代码，但是需要注意的是，这个计算器只是一个简单的示例，可能无法处理所有的输入和错误情况，也没有图形用户界面。

代码如下：

import scala.io.StdIn

object Calculator {
  def main(args: Array[String]): Unit = {
    println("Welcome to the Scala Calculator!")
    while (true) {
      val input = StdIn.readLine("Enter an equation (or exit to quit): ")
      if (input == "exit") {
        println("Thank you for using the Scala Calculator!")
        System.exit(0)
      }
      try {
        val result = Calculator.evaluate(input)
        println(s"Result: $result")
      } catch {
        case e: Exception => println(s"Error: ${e.getMessage}")
      }
    }
  }

  def evaluate(input: String): Double = {
    val tokens = input.split(" ")
    if (tokens.length != 3) {
      throw new IllegalArgumentException("Invalid input. Please enter an equation in the format: <number> <operator> <number>")
    }
    val leftOperand = tokens(0).toDouble
    val rightOperand = tokens(2).toDouble
    val operator = tokens(1)
    operator match {
      case "+" => leftOperand + rightOperand
      case "-" => leftOperand - rightOperand
      case "*" => leftOperand * rightOperand
      case "/" => leftOperand / rightOperand
      case _ => throw new IllegalArgumentException("Invalid operator. Please use one of the following: + - * /")
    }
  }
}

运行程序后，您可以输入一个算术表达式，例如：

Enter an equation (or exit to quit): 2 + 3
Result: 5.0

如果您输入的表达式无效，程序将抛出异常并显示错误消息：

Enter an equation (or exit to quit): 2 + 3 +
Error: Invalid input. Please enter an equation in the format: <number> <operator> <number>