strdup, strndup, strdupa, strndupa - duplicate a string
#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
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).
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.
- ENOMEM
- Insufficient memory available to allocate duplicate string.
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| strdup (), strndup (), strdupa (), strndupa () |
Thread safety |
MT-Safe |
strdup() conforms to SVr4, 4.3BSD, POSIX.1-2001.
strndup()
conforms to POSIX.1-2008.
strdupa() and
strndupa() are GNU
extensions.
alloca(3),
calloc(3),
free(3),
malloc(3),
realloc(3),
string(3),
wcsdup(3)