Manpages - strdup.3

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 <= 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 error.

ENOMEM

Insufficient memory available to allocate duplicate string.

For an explanation of the terms used in this section, see *attributes*(7).

*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)

This page is part of release 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.