反正有没有以指数方式迅速增加? [英] is there anyway to increment exponentially in swift?

问题描述

我正在尝试编写一个for循环，在该循环中我必须按指数递增.我正在使用 stride 函数，但无法正常工作.这是c ++代码，我正在尝试编写一个快速版本.

I am trying to write a for loop, where I have to increment exponentially. I am using stride function but it won't work. Here's c++ code, I am trying to write a swift version.

for(int m = 1; m< =高-低; m = 2 * m){}

您能帮我，快速编写这段代码吗?

can you help me, to write this code in swift version?

推荐答案

while循环可能是最简单的解决方案，但这是另一种选择:

A while-loop is probably the simplest solution, but here is an alternative:

for m in sequence(first: 1, next: { 2 * $0 }).prefix(while: { $0 <= high - low }) {
    print(m)
}

sequence()(延迟)生成序列1、2、4，...和 prefix(while:)将序列限制为给定范围.

sequence() (lazily) generates the sequence 1, 2, 4, ..., and prefix(while:) limits that sequence to the given range.

此方法的一个小优势是 m 仅在循环内部声明(这样以后就不会意外使用了)，这是一个 constant ，因此这样就不会在循环内无意中对其进行修改.

A slight advantage of this approach is that m is only declared inside the loop (so that it cannot be used later accidentally), and that is is a constant so that it cannot be inadvertently modified inside the loop.

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