++ u或u ++哪个更快？ [英] ++u or u++ which is faster?

问题描述

大家好，

如果U是用户定义的类型，最近我被问到关于++ U或U ++是否更快
的问题。答案是什么？


谢谢

解决方案

医生写道：

大家好，

如果U是用户定义的类型，最近我被问到关于++ U或U ++是否更快的问题。答案是什么？

谢谢

http://www.parashift.com/c++-faq-lit...html#faq-13.12


-

Sumit Rajan< sumitrajan AT亚历山大DOT cc>

医生张贴：
<尽管如此，我还是被问到如果U是用户定义类型，是否更快地使用++ U或U ++的问题。答案是什么？

谢谢

++你的速度更快。

总是使用++你。除非你需要，否则永远不要使用u ++。

-JKop

通常，operator ++（int）的实现如下： br />

T operator ++（int）

{

T tmp = * this;

+ + * this;

返回tmp;

}


如果编译器无法优化初始化暂时

然后使用u ++会变慢。这就是为什么通常更好地使用

预增量/预减量而不是后减量/后增量。


VH


" The Doctor" <做**** @ nospam.com>在消息中写道

新闻：Xn ********************************** @ 61.9 .191 .5 ...

大家好，

最近我被问到如果U是用户，++ U或U ++是否更快的问题定义的类型。答案是什么？

谢谢

Hi all,

Recently I was asked the question about whether ++U or U++ is
faster if U is a user defined type. What''s the answer?

Thank you

解决方案

The Doctor wrote:

Hi all,

Recently I was asked the question about whether ++U or U++ is
faster if U is a user defined type. What''s the answer?

Thank you

http://www.parashift.com/c++-faq-lit...html#faq-13.12

--
Sumit Rajan <sumitrajan AT alexandria DOT cc>

The Doctor posted:

Hi all,

Recently I was asked the question about whether ++U or U++ is
faster if U is a user defined type. What''s the answer?

Thank you

++u is faster.
Always use ++u. Never use u++ unless you need to.
-JKop

Usually operator ++ (int) is implemented like this:

T operator ++ (int)
{
T tmp = *this;
++*this;
return tmp;
}

If compiler isn''t able to optimize away the initialization of the temporary
then using u++ is slower. That''s why it is usually better to use
pre-increment/pre-decrement instead of post-decrement/post-increment.

VH

"The Doctor" <do****@nospam.com> wrote in message
news:Xn**********************************@61.9.191 .5...

Hi all,

Recently I was asked the question about whether ++U or U++ is
faster if U is a user defined type. What''s the answer?

Thank you

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