9.17

大数

大数用BigDecima

object base10 {
  def main(args: Array[String]): Unit = {


    val a=0.1
    val b=0.2
    val c=0.3
    println(1+2==3)
    println(0.1+0.2==0.3)
    println( BigDecimal(0.1)+BigDecimal(0.2)==BigDecimal(0.3))
    println(0.1+0.1==0.2)

  }

}

object base11 {

  def main(args: Array[String]): Unit = {
    val a=2147483647
    val b=1
    val c=a-(a-b)/2
    println(c)
  }

}

if语句

object base12 {

  def main(args: Array[String]): Unit = {
    println("请输入年龄：")
    val age =scala.io.StdIn.readInt()
    if (age>=18){
      println("成年")

    }else{
      println("未成年")
    }


  }

}

object base13 {

  def main(args: Array[String]): Unit = {
    print ("请输入正方形边长:")
    val a = scala.io.StdIn.readInt ()

    print ("请输入长方形的长:")
    val b = scala.io.StdIn.readInt ()

    print ("请输入长方形的宽:")
    val c = scala.io.StdIn.readInt ()

    if(b*c > a*a) { // 长方形面积大
      println ("长方形面积大")
    } else if (b*c < a*a) {
      println ("正方形面积大")
    } else {
      println ("一样大")
    }

  }

}