STDC_TRAILING_ZEROS(3)                        FreeBSD Library Functions Manual

NAME

     stdc_trailing_zeros - find the number of trailing zeros in an integer

SYNOPSIS

     /* -lc */
     #include <stdbit.h>

     unsigned int
     stdc_trailing_zeros_uc(unsigned char value);

     unsigned int
     stdc_trailing_zeros_us(unsigned short value);

     unsigned int
     stdc_trailing_zeros_ui(unsigned int value);

     unsigned int
     stdc_trailing_zeros_ul(unsigned long value);

     unsigned int
     stdc_trailing_zeros_ull(unsigned long long value);

     unsigned int
     stdc_trailing_zeros(value);

DESCRIPTION

     The stdc_trailing_zeros_type() family of functions returns the number of
     trailing zeros in value, where value is of type unsigned char, unsigned
     short, unsigned int, unsigned long, or unsigned long long for type being
     uc, us, ui, ul, or ull respectively.  The stdc_trailing_zeros(value)
     type-generic macro picks the appropriate stdc_trailing_zeros_type()
     function based on the type of value.

RETURN VALUES

     Returns the number of trailing zeros in value.  If value is all zeros,
     the total number of bits in the type of value is returned.

SEE ALSO

     ffs(3), stdbit(3), stdc_leading_zeros(3), stdc_trailing_ones(3),
     stdc_first_trailing_one(3)

STANDARDS

     The stdc_trailing_zeros_type() family of functions and the
     stdc_trailing_zeros() type-generic macro conform to ISO/IEC 9899:2024
     ("ISO C23").

HISTORY

     The stdc_trailing_zeros_type() family of functions and the
     stdc_trailing_zeros() type-generic macro were added in FreeBSD 15.1.

AUTHOR

     Robert Clausecker <fuz@FreeBSD.org>

FreeBSD 15.1-STABLE-HBSD       November 9, 2025         STDC_TRAILING_ZEROS(3)