strnlen(3) — Linux manual page

strnlen(3)              Library Functions Manual              strnlen(3)

NAME

       strnlen - determine the length of a fixed-size string

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <string.h>

       size_t strnlen(const char s[.maxlen], size_t maxlen);

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

       strnlen():
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
               _GNU_SOURCE

DESCRIPTION

       The strnlen() function returns the number of bytes in the string
       pointed to by s, excluding the terminating null byte ('\0'), but
       at most maxlen.  In doing this, strnlen() looks only at the first
       maxlen characters in the string pointed to by s and never beyond
       s[maxlen-1].

RETURN VALUE

       The strnlen() function returns strlen(s), if that is less than
       maxlen, or maxlen if there is no null terminating ('\0') among
       the first maxlen characters pointed to by s.

ATTRIBUTES

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

STANDARDS

       POSIX.1-2008.

HISTORY

       POSIX.1-2008.

SEE ALSO

       strlen(3)

COLOPHON

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Linux man-pages 6.9.1          2024-06-15                     strnlen(3)

Pages that refer to this page: strlen(3), wcsnlen(3), signal-safety(7)

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