Swift While和Repeat While循环语句用法 _swift循环语句

当迭代次数未知时, 将While和Repeat while循环用作for-in循环的替代方法。 while循环执行一组语句, 直到出现错误条件为止。当你不知道迭代次数时, 通常使用此循环。
Swift中有两种类型的循环：

while循环
重复While循环

Swift的While循环 Swift while循环在每次传递开始时评估其条件。
句法：

while (TestExpression) {// statements}

【Swift While和Repeat While循环语句用法】在这里, TestExpression是一个布尔表达式。如果是真的

在while循环内的语句被执行。
并且, 再次对TestExpression求值。

这个过程一直进行到TestExpression的值为假。当TestExpression获得错误条件时, while循环终止。
While循环流程图

文章图片
例：

var currentLevel:Int = 0, finalLevel:Int = 6let gameCompleted = truewhile (currentLevel < = finalLevel) {//play gameif gameCompleted {print("You have successfully completed level \(currentLevel)")currentLevel += 1}}//outside of while loopprint("Terminated! You are out of the game ")

输出

You have successfully completed level 0You have successfully completed level 1You have successfully completed level 2You have successfully completed level 3You have successfully completed level 4You have successfully completed level 5You have successfully completed level 6Terminated! You are out of the game

在上面的程序中, 执行while循环, 直到条件被评估为false为止, 并在获得false条件后立即终止。