scala> val d = 12
d: Int = 12scala> val e = 20
e: Int = 20scala> lazy val f = d * e
f: Int = <lazy>scala> f*12
res41: Int = 2880scala> f
res42: Int = 240

scala> val y:Int = 20
y: Int = 20scala> val x = "asd"
x: String = asd

{exp1; exp2}

{exp1exp2
}

def functionName(param: paramType):returnType = {// function body: expressions
}

object Hello {def helloDemo(name: String) = {s"Hello,${ name }"}def add(x:Int, y:Int): Int = {x+y}def main(arg: Array[String]) = {println(helloDemo("Yu Hang"))println(s"X + Y Result is ${add(12,34)}")}
}

scala> if(true) 1 else 2
res44: Int = 1scala> if(false) 3 else 4
res45: Int = 4scala> val a = 1
a: Int = 1scala> if(a == 1) a
res46: AnyVal = 1scala> if(a!= 1) a
res47: AnyVal = ()scala> if(a!=1) "not one" else a
res48: Any = 1scala> if(a!=1) "not one"
res49: Any = ()

println("正常的for遍历：")
for( s <- l) {   // generatorprintln(s)
}
println("\n带有 filter 的for遍历：")
for( s <- l          // generatorif(s.length>4)  // filter
) {println(s)
}
println("\n带有 filter 的for遍历：")
val result_for = for{s <- l              // generators1 = s.toUpperCase()  // variable bindingif(s1 != "")
} yield (s1)          // generator new collection
for( item <- result_for ) println(item)

try {}
catch {}
finally {}

try {Integer.parseInt("dog")
} catch {case _ => 0
} finally {println("always be printed")
}

exp match {case p1 => val1case p2 => val2...case _ => valn
}

val code = 3val result_match = code match {case 1 => println("one")case 2 => println("two")case 3 => println("three")case _ => println("other")
}

def foo( asd: Int)          // Call By Value
def foo( asd: => Int)    // Call By Name

def text1(x: Int,  y: Int): Int = x*xdef text2(x: => Int, y: => Int): Int = x*x

test1(3+4, 8)
test1(7, 8)                //test1 是Call By Value,首先会先算出参数
7*7
49test2(3+4, 8)
(3+4)*(3+4)           // test2是 Call By Name, 直接把3+4传入test2，表达式替换x变量
7*(3+4)
7*7
49

test1(7， 2*4)test1(7, 8)              //test1 是Call By Value,首先会先算出参数 2*4，再对x、y进行赋值
7*7
49test2(7， 2*4)       // test2是 Call By Name, 直接把2*4传入test2，表达式替换y变量
7*7                      // 2*4 没用到，所以一直不需要进行计算
49