什么是更高效的i ++或++ i？ [英] What is more efficient i++ or ++i?

问题描述

完全重复：在C ++中i ++和++ i之间的性能差异吗？

确切重复：循环中i ++和++ i之间的区别？

更有效的i ++或++ i？

What is more efficient i++ or ++i?

我只用在Java和C / C ++中，但我真的要求所有的语言，这是实现。

I have only used this in Java and C/C++, but I am really asking for all languages that this is implemented in.

在大学，我有一个教授展示我们认为++ i更高效，但已经有几年了，我想从SO社区获得输入。

In college I had a professor show us that ++i was more efficient but it has been a couple years and I would like to get input from the SO community.

推荐答案

p> i ++：

• 创建i的临时副本


• 增加i


• 返回临时副本

++ i：

• 增加i


• 返回i

，这是非常可能的结果程序集是完全相同的，但++ i是更有效率。

With optimizations on, it is quite possible that the resulting assembly is identical, however ++i is more efficient.

编辑：记住在C ++，我可以是任何对象支持前缀和后缀++运算符。对于复杂对象，临时复制成本不可忽略。

edit : keep in mind that in C++, i may be whatever object that support the prefix and postfix ++ operator. For complex objects, the temporary copy cost is non negligible.

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