strdup(3)                  Library Functions Manual                  strdup(3)

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

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <string.h>

       char *strdup(const char *s);

       char *strndup(const char s[.n], size_t n);
       char *strdupa(const char *s);
       char *strndupa(const char s[.n], 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 <= 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.

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 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 (), strndupa | Thread safety | MT-Safe |
       |()                                          |               |         |
       +--------------------------------------------+---------------+---------+
STANDARDS
       strdup()
       strndup()
              POSIX.1-2008.

       strdupa()
       strndupa()
              GNU.

HISTORY
       strdup()
              SVr4, 4.3BSD-Reno, POSIX.1-2001.

       strndup()
              POSIX.1-2008.

       strdupa()
       strndupa()
              GNU.

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

Linux man-pages 6.7               2023-10-31                         strdup(3)