Kotlin for循环用于多次迭代程序的一部分。它遍历数组,范围,集合或任何提供迭代的内容。 Kotlin for循环等效于C#等语言中的foreach循环。
Kotlin中for循环的语法:
for (item in collection){ //body of loop }
让无涯教程看看迭代数组元素的简单示例。
fun main(args : Array<String>) { val marks = arrayOf(80,85,60,90,70) for(item in marks){ println(item) } }
输出:
80 85 60 90 70
如果for循环的主体只包含一行语句,则无需在括号中括起来 {}。
fun main(args : Array<String>) { val marks = arrayOf(80,85,60,90,70) for(item in marks) println(item) }
基于数组的indices(索引)迭代数组的元素。例如:
fun main(args : Array<String>) { val marks = arrayOf(80,85,60,90,70) for(item in marks.indices) println("marks[$item]: "+ marks[item]) }
输出:
marks[0]: 80 marks[1]: 85 marks[2]: 60 marks[3]: 90 marks[4]: 70
让无涯教程看一下迭代范围元素的示例。
fun main(args : Array) { print("for (i in 1..5) print(i) = ") for (i in 1..5) print(i) println() print("for (i in 5..1) print(i) = ") for (i in 5..1) print(i) //prints nothing println() print("for (i in 5 downTo 1) print(i) = ") for (i in 5 downTo 1) print(i) println() print("for (i in 5 downTo 2) print(i) = ") for (i in 5 downTo 2) print(i) println() print("for (i in 1..5 step 2) print(i) = ") for (i in 1..5 step 2) print(i) println() print("for (i in 5 downTo 1 step 2) print(i) = ") for (i in 5 downTo 1 step 2) print(i) }
输出:
for (i in 1..5) print(i) = 12345 for (i in 5..1) print(i) = for (i in 5 downTo 1) print(i) = 54321 for (i in 5 downTo 2) print(i) = 5432 for (i in 1..5 step 2) print(i) = 135 for (i in 5 downTo 1 step 2) print(i) = 531
祝学习愉快!(内容编辑有误?请选中要编辑内容 -> 右键 -> 修改 -> 提交!)