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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | STANDARDS | CAVEATS | SEE ALSO | COLOPHON |
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powerof2(3) Library Functions Manual powerof2(3)
powerof2 - test if a value is a power of 2
Standard C library (libc)
#include <sys/param.h>
int powerof2(x);
This macro returns true if x is a power of 2, and false otherwise.
0 is considered a power of 2. This can make sense considering
wrapping of unsigned integers, and has interesting properties.
True or false, if x is a power of 2 or not, respectively.
BSD.
The arguments may be evaluated more than once.
Because this macro is implemented using bitwise operations, some
negative values can invoke undefined behavior. For example, the
following invokes undefined behavior: powerof2(INT_MIN);. Call it
only with unsigned types to be safe.
stdc_bit_ceil(3), stdc_bit_floor(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
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⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
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Linux man-pages 6.15 2025-05-17 powerof2(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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