strdup

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



NAME
       strdup, strndup, strdupa, strndupa - duplicate a string

SYNOPSIS
       #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)):

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

DESCRIPTION
       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
       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
       ENOMEM Insufficient memory available to allocate duplicate string.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────────┬───────────────┬─────────┐
       │Interface                       Attribute     Value   │
       ├────────────────────────────────┼───────────────┼─────────┤
       │strdup(), strndup(), strdupa(), │ Thread safety │ MT-Safe │
       │strndupa()                      │               │         │
       └────────────────────────────────┴───────────────┴─────────┘

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

SEE ALSO
       alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3),
       wcsdup(3)

COLOPHON
       This page is part of release 5.10 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
       https://www.kernel.org/doc/man-pages/.



GNU                                2019-03-06                          STRDUP(3)