strdup(3p) — Linux manual page

STRDUP(3P)              POSIX Programmer's Manual             STRDUP(3P)

PROLOG

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME

       strdup, strndup — duplicate a specific number of bytes from a
       string

SYNOPSIS

       #include <string.h>

       char *strdup(const char *s);
       char *strndup(const char *s, size_t size);

DESCRIPTION

       The strdup() function shall return a pointer to a new string,
       which is a duplicate of the string pointed to by s.  The returned
       pointer can be passed to free().  A null pointer is returned if
       the new string cannot be created.

       The strndup() function shall be equivalent to the strdup()
       function, duplicating the provided s in a new block of memory
       allocated as if by using malloc(), with the exception being that
       strndup() copies at most size plus one bytes into the newly
       allocated memory, terminating the new string with a NUL
       character. If the length of s is larger than size, only size
       bytes shall be duplicated. If size is larger than the length of
       s, all bytes in s shall be copied into the new memory buffer,
       including the terminating NUL character. The newly created string
       shall always be properly terminated.

RETURN VALUE

       The strdup() function shall return a pointer to a new string on
       success. Otherwise, it shall return a null pointer and set errno
       to indicate the error.

       Upon successful completion, the strndup() function shall return a
       pointer to the newly allocated memory containing the duplicated
       string. Otherwise, it shall return a null pointer and set errno
       to indicate the error.

ERRORS

       These functions shall fail if:

       ENOMEM Storage space available is insufficient.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       For functions that allocate memory as if by malloc(), the
       application should release such memory when it is no longer
       required by a call to free().  For strdup() and strndup(), this
       is the return value.

       Implementations are free to malloc() a buffer containing either
       (size + 1) bytes or (strnlen( s, size) + 1) bytes. Applications
       should not assume that strndup() will allocate (size + 1) bytes
       when strlen( s) is smaller than size.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       free(3p), wcsdup(3p)

       The Base Definitions volume of POSIX.1‐2017, string.h(0p)

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                        STRDUP(3P)

Pages that refer to this page: string.h(0p), strndup(3p), wcsdup(3p)

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