strdup(3)

NAME#

strdup, strndup, strdupa, strndupa - duplicate a string

LIBRARY#

Standard C library (libc, -lc)

SYNOPSIS#

#include <string.h>

char *strdup(const char *\ns\n);

char *strndup(const char \ns\n[.\nn\n], size_t \nn\n);\n
\nchar *strdupa(const char *\ns\n);\n
\nchar *strndupa(const char \ns\n[.\nn\n], size_t \nn\n);

strdup():

\n
    _XOPEN_SOURCE >= 500
\n
        || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
\n
        || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE

strndup():

\n
    Since glibc 2.10:
\n
        _POSIX_C_SOURCE >= 200809L
\n
    Before glibc 2.10:
\n
        _GNU_SOURCE

strdupa(), strndupa():

\n
    _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).

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)