strdup(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON

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)):

       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         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
       attributes(7).

       ┌────────────────────────────────┬───────────────┬─────────┐
       │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),
       wcsdup(3)

COLOPHON         top

       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)

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