roundup(3) — Linux manual page

roundup(3)               Library Functions Manual              roundup(3)

NAME         top

       roundup - round up in steps

LIBRARY         top

       Standard C library (libc)

SYNOPSIS         top

       #include <sys/param.h>

       roundup(x, step);

DESCRIPTION         top

       This macro rounds x to the nearest multiple of step that is not
       less than x.

       It is typically used for rounding up a pointer to align it or
       increasing a buffer to be allocated.

       This API is not designed to be generic, and doesn't work in some
       cases that are not important for the typical use cases described
       above.  See CAVEATS.

RETURN VALUE         top

       This macro returns the rounded value.

STANDARDS         top

       None.

CAVEATS         top

       The arguments may be evaluated more than once.

       x should be nonnegative, and step should be positive.

       If x + step would overflow or wrap around, the behavior is
       undefined.

SEE ALSO         top

       ceil(3), floor(3), lrint(3), rint(3), lround(3), round(3)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                     roundup(3)

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