什么时候交换两个数字而不使用第三个变量？ [英] When would you swap two numbers without using a third variable?

问题描述

我已经阅读了几个资源，讨论如何交换两个数字，而不使用第三个变量。这些是最相关的几个：

• 如何在不使用任何if条件，转换或其他变量的情况下交换两个整数变量？ li>
  
• Potential Problem inSwapping values of two variables without using a third variable


• 在不使用第三个变量的情况下交换两个整数


• http://www.geeksforgeeks.org/swap-two-numbers-without-using-temporary-variable /

我理解为什么在大多数情况下使用描述的方法没有意义：代码变得混乱并且难以读取，并且通常比使用第三temp变量的解决方案执行得更慢。然而，我没有发现任何问题讨论双变量方法在实践中的任何好处。

解决方案

在这种情况下，这一点它只是一个整洁的技巧。速度 - 如果它是有意义的，虽然你的编译器将识别一个正常交换和适当地优化（但不保证它会识别奇怪 xor 并适当优化）。

I have read several sources that discuss how to swap two numbers without using a third variable. These are a few of the most relevant:

• How do you swap two integer variables without using any if conditions, casting, or additional variables?
• Potential Problem in "Swapping values of two variables without using a third variable"
• Swap two integers without using a third variable
• http://www.geeksforgeeks.org/swap-two-numbers-without-using-temporary-variable/

I understand why it doesn't make sense to use the described methods in most cases: the code becomes cluttered and difficult to read and will usually execute more slowly than a solution utilizing a third "temp" variable. However, none of the questions I have found discuss any benefits of the two-variable methods in practice. Do they have any redeeming qualities or benefits(historical or contemporary), or are they only useful as obscure programming trivia?

解决方案

At this point it's just a neat trick. Speed-wise if it makes sense though your compiler will recognize a normal swap and optimize it appropriately (but no guarantees that it will recognize weird xoring and optimize that appropriately).

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