C编程相关问题 [英] C programming related question Question

问题描述

给出单行C表达式以测试数字是否为2的幂.[不允许循环]?

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

推荐答案

isPow2 = x && !( (x-1) & x );

请参阅此处以获得说明:
http://bytes.com/topic/c/answers/213306- test-whether-number-power-2-a [ ^ ]

See here for an explanation:
http://bytes.com/topic/c/answers/213306-test-whether-number-power-2-a[^]

v && !(v & (v - 1));

来源: http://graphics.stanford.edu/~seander/bithacks.html [ ^ ]

Source: http://graphics.stanford.edu/~seander/bithacks.html[^]

返回(v ％2 == 0?true:false);

return (v % 2 == 0 ? true : false);

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