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Scala学习笔记(3)-表达式归纳

语法:使用表达式定义值和变量

      val <identifier>[:<type>]=<expression>  字面值类型

      var <identifier>[:<type>]=<expression>  变量类型

实例1:

同一级定义类型

scala> val x=5*20;val amount=x+10

x: Int = 100
amount: Int = 110

块局部定义(建议采用)

scala> val amount={val x=5*20;x+10}
amount: Int = 110

写法2:

scala> val amount={
| val x=5*20
| x+10
| }
amount: Int = 110

 表达式嵌套:

scala> {val a=1;{val b=a*2;{val c=b+4;c}}}
res11: Int = 6

实例2-if-else:

     if(<Boolean expression>)<expression>

     else <expression>

scala> if(47%3 >0) print("not a multipul of 3")

scala> val result=if(false) "what does this return?"
result: Any = ()  //未定类型,可能是String或Unit

scala> val x=10;val y=20
x: Int = 10
y: Int = 20

scala> val max=if(x>y)x else y
max: Int = 20

匹配表达式(类似的Switch表达式)

     <expression> match{

     case <pattern match>=><expression>

     }

 

Scala学习笔记(3)-表达式归纳