strdup, strndup, strdupa, strndupa − duplicate a string
Standard C library (libc, −lc)
#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
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.
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.
ENOMEM |
Insufficient memory available to allocate duplicate string. |
For an explanation of the terms used in this section, see attributes(7).
strdup()
strndup()
POSIX.1-2008.
strdupa()
strndupa()
GNU.
strdup()
SVr4, 4.3BSD-Reno, POSIX.1-2001.
strndup()
POSIX.1-2008.
strdupa()
strndupa()
GNU.
alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3), wcsdup(3)