退出带有负整数的 while 循环 [英] exiting a while loop with a negative integer

问题描述

我想在用户输入任意大小的负数时退出 while().当用户输入负数时，在循环开始时我需要什么样的条件才能让循环退出?

I want to exit a while() when the user enters a negative number of any size. What kind of condition would I need at the start of the loop to get the loop to exit when the user enters a negative number?

推荐答案

那么，什么是负数?它是一个小于零的数字(称为 x)，或者象征性地，x <0.如果 x 小于零，则为真.如果不是，那就是假的.

Well, what is a negative number? It's a number (call it x) that is less than zero, or symbolically, x < 0. If x is less than zero, then this is true. If not, then it is false.

您可以无限循环并在满足此条件时中断:

You can loop endlessly and break when this condition is met:

while (1) {
  if (x < 0) {
    break;
  }

  ...
}

但我更喜欢在 while 循环本身中使用与该条件相反的条件:

But I prefer to just use the opposite of that condition in the while loop itself:

 while (x >= 0) {
   ...

当条件为真时，循环继续.当它为假(并且您的原始条件为真，因为这两个相反)时，循环中断.

While the condition is true, then the loop continues. When it is false (and your original condition is true, as these two are opposite), the loop breaks.

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