〜简单数字问题 [英] ~Simple number problem

问题描述

如果int介于0到29之间，则返回0.如果30-59，则返回30.

可以使用单行数学表达式，没有IF语句或位来执行此操作

换班？ TIA


-

William Stacey [MVP]

if int is between 0-29 return 0. If 30-59, return 30.
Can you do this with a one line math expression and no IF statements or bit
shifting? TIA

--
William Stacey [MVP]

推荐答案

int i =（value / 30）* 30;

int i = (value / 30) * 30;

Math.Floor（30 / x）* 30;


哪个比CPU好得多？


y =（x> 30？30：0）;


是否存在这些限制的原因（如果 - 等等......）或这只是

智力运动？


William Stacey [ MVP] QUOT; <无线************ @ gmail.com>在消息中写道

news：uS ************** @ tk2msftngp13.phx.gbl ...

Math.Floor(30 / x)*30;

Which is much more expensive CPU-wise than

y = (x > 30 ? 30 : 0);

Is there a reason for these constraints (no if-then etc...) or is this just
intellectial exercise?

"William Stacey [MVP]" <wi************@gmail.com> wrote in message
news:uS**************@tk2msftngp13.phx.gbl...

如果int介于0之间-29返回0.如果30-59，则返回30.
你可以用一行数学表达式，没有IF语句或
位移动吗？ TIA

-
William Stacey [MVP]

if int is between 0-29 return 0. If 30-59, return 30.
Can you do this with a one line math expression and no IF statements or
bit
shifting? TIA

--
William Stacey [MVP]

> Math.Floor（30 / x）* 30;

> Math.Floor(30 / x)*30;

这比（/ x> 30？30：0）更加昂贵的CPU（ 30？30：0）;

Which is much more expensive CPU-wise than
y = (x > 30 ? 30 : 0);

实际上我应该关闭这个...编译器团队可能在库中有一个

超快速的Floor（）实现（即，强制转换） to int）和

我只是在这里陈述未经证实的想法......

Actually I should shut up about this... The compiler team might have a
super-fast implementation of Floor() in the library (ie, cast to int) and
I''m just stating unsubstantiated ideas here...

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