strdup(3) — Linux manual page


STRDUP(3)                 Linux Programmer's Manual                STRDUP(3)

NAME         top

       strdup, strndup, strdupa, strndupa - duplicate a string

SYNOPSIS         top

       #include <string.h>

       char *strdup(const char *s);

       char *strndup(const char *s, size_t n);
       char *strdupa(const char *s);
       char *strndupa(const char *s, size_t n);

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

           _XOPEN_SOURCE >= 500
               || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:
       strdupa(), strndupa(): _GNU_SOURCE

DESCRIPTION         top

       The strdup() function returns a pointer to a new string which is a
       duplicate of the string s.  Memory for the new string is obtained
       with malloc(3), and can be freed with free(3).

       The strndup() function is similar, but copies at most n bytes.  If s
       is longer than n, only n bytes are copied, and a terminating null
       byte ('\0') is added.

       strdupa() and strndupa() are similar, but use alloca(3) to allocate
       the buffer.  They are available only when using the GNU GCC suite,
       and suffer from the same limitations described in alloca(3).

RETURN VALUE         top

       On success, the strdup() function returns a pointer to the duplicated
       string.  It returns NULL if insufficient memory was available, with
       errno set to indicate the cause of the error.

ERRORS         top

       ENOMEM Insufficient memory available to allocate duplicate string.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see

       │Interface                       Attribute     Value   │
       │strdup(), strndup(), strdupa(), │ Thread safety │ MT-Safe │
       │strndupa()                      │               │         │

CONFORMING TO         top

       strdup() conforms to SVr4, 4.3BSD, POSIX.1-2001.  strndup() conforms
       to POSIX.1-2008.  strdupa() and strndupa() are GNU extensions.

SEE ALSO         top

       alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3),

COLOPHON         top

       This page is part of release 5.09 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

GNU                              2019-03-06                        STRDUP(3)

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