1.1 范围数据循环(To)

i 将会从1-3循环，前后闭合

  1. for(i <- 1 to 3){
  2.    print(i + " ")
  3. }

1.2 范围数据循环( Until )

i 将会从 1-(3-1)循环，前闭后开

  1. for(i <- 1 until 3){
  2.   print(i + " ")
  3. }

1.3 循环守卫

进入代码块前，先执行判断（if != 2），满足执行代码块

  1. for(i <- 1 to 3 if != 2){
  2.   print(i + " ")
  3. }

1.4 循环步长

by 2 相当于 for（i = 1 ； i < 10 ; i+=2）

  1. for(i <- 1 to 10 by 2){
  2.   println("i = " + i)
  3. }

1.5 嵌套循环

  1. for(i <- 1 to 3; j <- 1 to 3){
  2.   println("i = " + i + " j =" + j)
  3. }

  1.  相当于
  2.  for（.....）{      
  3.        for (.....) {  
  4.         }             
  5.   }

1.6 引入变量

  1. for( i <- 1 to 3 ; j = 4- j){
  2.   println(" i = " + i + " j = "+ j)
  3. }
  1. 相当于
  2.  for（i <- 1 to 3 ）{
  3.        var  j = 4 - j
  4.        println(" i = " + i + " j = "+ j)
  5. }

1.7 倒序打印

  1. for(i <- 1 to 10 reverse){
  2.    println(i)
  3. }
  1. 相当于
  2. for( i <- 10 to 1){
  4. }