STRDUP(3) OpenBSD Programmer's Manual STRDUP(3)


strdup, strndupsave a copy of a string


#include <string.h>

char *
strdup(const char *s);

char *
strndup(const char *s, size_t maxlen);


The strdup() function allocates sufficient memory for a copy of the string s, does the copy, and returns a pointer to it. The pointer may subsequently be used as an argument to the function free(3).

The strndup() function behaves similarly to strdup but only copies up to maxlen characters from s. The resulting string is always NUL-terminated.

If insufficient memory is available, NULL is returned.


The following will point p to an allocated area of memory containing the NUL-terminated string “foobar”:

char *p; 
p = strdup("foobar"); 
if (p == NULL) 
	err(1, NULL);


The strdup() and strndup() functions may fail and set the external variable errno for any of the errors specified for the library function malloc(3).


free(3), malloc(3), strcpy(3), strlcpy(3), strlen(3), wcsdup(3)


The strdup() and strndup() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).


The strdup() function first appeared in 4.3BSD-Reno. The strndup() function appeared in glibc 2.0, was reimplemented for NetBSD 4.0, and ported to OpenBSD 4.8.
June 5, 2013 OpenBSD 5.6