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ffs(3)                  Library Functions Manual                  ffs(3)

ИМЯ

       ffs, ffsl, ffsll - find first bit set in a word

БИБЛИОТЕКА

       Standard C library (libc, -lc)

СИНТАКСИС

       #include <strings.h>

       int ffs(int i);
       int ffsl(long i);
       int ffsll(long long i);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       ffs():
           Since glibc 2.12:
               _XOPEN_SOURCE >= 700
                   || ! (_POSIX_C_SOURCE >= 200809L)
                   || /* glibc >= 2.19: */ _DEFAULT_SOURCE
                   || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
           Before glibc 2.12:
               none

       ffsl(), ffsll():
           Since glibc 2.27:
               _DEFAULT_SOURCE
           Before glibc 2.27:
               _GNU_SOURCE

ОПИСАНИЕ

       The ffs() function returns the position of the first (least
       significant) bit set in the word i.  The least significant bit is
       position 1 and the most significant position is, for example, 32
       or 64.  The functions ffsll() and ffsl() do the same but take
       arguments of possibly different size.

ЗНАЧЕНИЕ, ВОЗВРАЩАЕМОЕ ФУНКЦИЕЙ

       These functions return the position of the first bit set, or 0 if
       no bits are set in i.

АТРИБУТЫ

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                           │ Attribute     │ Value   │
       ├─────────────────────────────────────┼───────────────┼─────────┤
       │ ffs(), ffsl(), ffsll()              │ Thread safety │ MT-Safe │
       └─────────────────────────────────────┴───────────────┴─────────┘

СТАНДАРТЫ

       ffs()  POSIX.1-2001, POSIX.1-2008, 4.3BSD.

       ffsl()
       ffsll()
              GNU.

СМОТРИТЕ ТАКЖЕ

       memchr(3)

КОЛОФОН

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Linux man-pages 6.9.1          2024-05-02                         ffs(3)

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