| strdup(3) | Library Functions Manual | strdup(3) |
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);
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.
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| strdup (), strndup (), strdupa (), strndupa () | Thread safety | MT-Safe |
alloca(3), calloc(3), free(3), malloc(3), realloc(3), string(3), wcsdup(3)
| 2023-10-31 | Linux man-pages 6.7 |