寒假学习日报（三十）

package com.chapter01.inputcon

object forcon {
  def main(args: Array[String]): Unit = {
    print("to循环：")
    //[1,5]
    //这里i相当于val变量，可以写成纯函数
    for (i <- 1 to 5) {
      print(i + " ")
    }
    println()
    print("集合循环：")
    //集合
    val list = List("hello", 5, 10, "OK")
    for (item <- list) {
      print(item + " ")
    }
    println()
    print("until循环：")
    //[1,5)
    for (i <- 1 until 5) {
      print(i + " ")
    }
    println()
    print("循环守卫：")
    //循环守卫
    for (i <- 1 to 5 if i != 3) {
      print(i + " ")
    }
    println()
    print("引入变量：")
    //引入变量
    for (i <- 1 to 5; j = 5 - i) {
      print(j + " ")
    }
    println()
    print("嵌套循环：")
    //嵌套循环
    for (i <- 1 to 3; j <- 1 to 3) {
      print(i + "|" + j + " ")
    }
    println()
    print("循环返回值：")
    //循环返回值
    //可以对返回值i进行处理
    var res = for (i <- 1 to 10) yield {
      if (i % 2 == 0) {
        i
      } else {
        "不是偶数"
      }
    }
    println(res)
    println("花括号可以替换小括号：")
    //花括号可以替换小括号
    for (i <- 1 to 5; j = i * 2) {
      print(i + "|" + j + " ")
    }
    //等价于
    println()
    for {i <- 1 to 5
         j = i * 2} {
      print(i + "|" + j + " ")
    }
    println()
    print("控制步长----Range：")
    //Range参数：起点，终点，步数
    for (i <- Range(1, 10, 2)) {
      print(i + " ")
    }
    println()
    print("控制步长----for循环守卫：")
    for (i <- 1 to 10 if i % 2 == 1) {
      print(i + " ")
    }
  }
}