|NO.Z.00009|——————————|BigDataEnd|——|Hadoop&Scala.V09|——|Scala.v09|Scala编程|块表达式|赋值语句|

一、块表达式和赋值语句

### --- 块表达式和赋值语句

~~~     {} 块包含一系列表达式，其结果也是一个表达式，块中最后一个表达式的值就是块的值。
~~~     赋值语句返回Unit类型，代表没有值；

### --- 编程需求
val x1 = 1
val y1 = 1
val x2 = 0
val y2 = 0
val distance = {
val dx = x1 - x2
val dy = y1 - y2
math.sqrt(dx*dx + dy*dy)
}

~~~     # 赋值语句的值是Unit类型，不要把它们串接在一起。x的值是什么?
var y = 0
val x = y = 1

### --- 编程代码

package yanqi.cn.part01

/**
 * {}块表达式，可以包含一系列表达式，块中最后一个表达式的值就是整个块的值
 */
object BlockDemo {
  def main(args: Array[String]): Unit = {
    val x1 = 1
    val y1 = 2
    val x2 = 3
    val y2 = 4
    val distance = {
      val dx = x2 - x1
      val dy = y2 - y1

      math.sqrt(dx * dx + dy * dy)
    }
    println(distance)

    //赋值语句的值是Unit类型的
    var y = 0
    val x = y = 1
    println(x)
  }
}

### --- 编译打印

D:\JAVA\jdk1.8.0_231\bin\java.exe "-javaagent:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\lib\idea_rt.jar=51866:D:\IntelliJIDEA\IntelliJ IDEA 2019.3.3\bin" -Dfile.encoding=UTF-8 -classpath D:\JAVA\jdk1.8.0_231\jre\lib\charsets.jar;D:\JAVA\jdk1.8.0_231\jre\lib\deploy.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\access-bridge-64.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\cldrdata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\dnsns.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jaccess.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\jfxrt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\localedata.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\nashorn.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunec.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunjce_provider.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunmscapi.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\sunpkcs11.jar;D:\JAVA\jdk1.8.0_231\jre\lib\ext\zipfs.jar;D:\JAVA\jdk1.8.0_231\jre\lib\javaws.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jce.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfr.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jfxswt.jar;D:\JAVA\jdk1.8.0_231\jre\lib\jsse.jar;D:\JAVA\jdk1.8.0_231\jre\lib\management-agent.jar;D:\JAVA\jdk1.8.0_231\jre\lib\plugin.jar;D:\JAVA\jdk1.8.0_231\jre\lib\resources.jar;D:\JAVA\jdk1.8.0_231\jre\lib\rt.jar;E:\NO.Z.10000——javaproject\NO.Z.00002.Hadoop\ScalaPro\out\production\ScalaPro;D:\JAVA\scala-2.12.2\lib\scala-library.jar;D:\JAVA\scala-2.12.2\lib\scala-reflect.jar yanqi.cn.part01.BlockDemo
2.8284271247461903
()

Process finished with exit code 0

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Walter Savage Landor:strove with none,for none was worth my strife.Nature I loved and, next to Nature, Art:I warm'd both hands before the fire of life.It sinks, and I am ready to depart

                                                                                                                                                   ——W.S.Landor

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