Name

strdup, strndup, strdupa, strndupa — duplicate a string

Synopsis

#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);
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
strdup():
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500
strndup(), strdupa(), strndupa():
_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 only copies at most n characters. If s is longer than n, only n characters 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 only available when using the GNU GCC suite, and suffer from the same limitations described in alloca(3).

RETURN VALUE

The strdup() function returns a pointer to the duplicated string, or NULL if insufficient memory was available.

ERRORS

ENOMEM

Insufficient memory available to allocate duplicate string.

CONFORMING TO

strdup() conforms to SVr4, 4.3BSD, POSIX.1-2001. strndup(), strdupa(), and strndupa() are GNU extensions.

SEE ALSO

alloca(3), calloc(3), free(3), malloc(3), realloc(3), wcsdup(3)

COLOPHON

This page is part of release 2.79 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


  Copyright 1993 David Metcalfe (davidprism.demon.co.uk)

Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date.  The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein.  The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.

Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.

References consulted:
    Linux libc source code
    Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
    386BSD man pages
Modified Sun Jul 25 10:41:34 1993 by Rik Faith (faithcs.unc.edu)
Modified Wed Oct 17 01:12:26 2001 by John Levon <mozcompsoc.man.ac.uk>