测试一个数是否是2的幂 [英] to test whether a number is a power of 2

问题描述

给出一个单行C表达式来测试一个数字是否是2的幂。

[不允许循环]

解决方案

ravi写道：

给出一个单行C表达式来测试一个数字是否是2的幂。

[不允许循环]

做自己的作业。


Brian

ravi写道：

>

给出单行C表达式来测试一个数字是否是一个电源

of 2. [不允许循环]

对于无符号整数：


if（！（（n - 1）& n））put（n ispower of 2）;


-

< http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt>

< http://www.securityfocus.com/columnists/423>

< http://www.aaxnet.com/editor/edit043.html>

cbfalconer at ma ineline dot net

-

通过 http://www.teranews.com

ravi写道：

给出单行C表达式来测试一个数字是否为2的幂。

[不允许循环]

static inline int

is_power_of_2（int x）

{

return（（x& （x - 1））== 0）;

}

-

------------ -------------------------------------------------- ---

Erik de Castro Lopo

--------------------------- --------------------------------------

哈马斯：伊斯兰教将征服美国和英国。

- http://www.pmw.org.il/LatestBulletins.htm#b220606

Give a one-line C expression to test whether a number is a power of 2.
[No loops allowed]

解决方案

ravi wrote:

Give a one-line C expression to test whether a number is a power of 2.
[No loops allowed]

Do your own homework.

Brian

ravi wrote:

>
Give a one-line C expression to test whether a number is a power
of 2. [No loops allowed]

For unsigned integers:

if (!((n - 1) & n)) puts("n is power of 2");

--
<http://www.cs.auckland.ac.nz/~pgut001/pubs/vista_cost.txt>
<http://www.securityfocus.com/columnists/423>
<http://www.aaxnet.com/editor/edit043.html>
cbfalconer at maineline dot net
--
Posted via a free Usenet account from http://www.teranews.com

ravi wrote:

Give a one-line C expression to test whether a number is a power of 2.
[No loops allowed]

static inline int
is_power_of_2 (int x)
{
return ((x & (x - 1)) == 0) ;
}
--
-----------------------------------------------------------------
Erik de Castro Lopo
-----------------------------------------------------------------
"Hamas: Islam will conquer US and Britain."
-- http://www.pmw.org.il/LatestBulletins.htm#b220606

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