powerof2(3)

1powerof2(3)                Library Functions Manual                powerof2(3)
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NAME

6       powerof2 - test if a value is a power of 2
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LIBRARY

9       Standard C library (libc)
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SYNOPSIS

12       #include <sys/param.h>
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14       int powerof2(x);
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DESCRIPTION

17       This macro returns true if x is a power of 2, and false otherwise.
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19       0 is considered a power of 2.  This can make sense considering wrapping
20       of unsigned integers, and has interesting properties.
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RETURN VALUE

23       True or false, if x is a power of 2 or not, respectively.
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STANDARDS

26       BSD.
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CAVEATS

29       The arguments may be evaluated more than once.
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31       Because this macro is implemented using bitwise operations, some  nega‐
32       tive  values can invoke undefined behavior.  For example, the following
33       invokes undefined behavior: powerof2(INT_MIN);.  Call it only with  un‐
34       signed types to be safe.
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