1STRDUP(3P)                 POSIX Programmer's Manual                STRDUP(3P)
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PROLOG

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

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

15       #include <string.h>
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17       char *strdup(const char *s);
18       char *strndup(const char *s, size_t size);
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DESCRIPTION

21       The strdup() function shall return a pointer to a new string, which  is
22       a duplicate of the string pointed to by s.  The returned pointer can be
23       passed to free().  A null pointer is returned if the new string  cannot
24       be created.
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26       The  strndup()  function  shall be equivalent to the strdup() function,
27       duplicating the provided s in a new block of memory allocated as if  by
28       using  malloc(), with the exception being that strndup() copies at most
29       size plus one bytes into the newly allocated  memory,  terminating  the
30       new  string  with  a  NUL  character. If the length of s is larger than
31       size, only size bytes shall be duplicated. If size is larger  than  the
32       length of s, all bytes in s shall be copied into the new memory buffer,
33       including the terminating NUL character. The newly created string shall
34       always be properly terminated.
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RETURN VALUE

37       The  strdup()  function  shall return a pointer to a new string on suc‐
38       cess. Otherwise, it shall return a null pointer and set errno to  indi‐
39       cate the error.
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41       Upon  successful  completion,  the  strndup()  function  shall return a
42       pointer to the newly allocated memory containing the duplicated string.
43       Otherwise, it shall return a null pointer and set errno to indicate the
44       error.
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ERRORS

47       These functions shall fail if:
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49       ENOMEM Storage space available is insufficient.
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51       The following sections are informative.
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EXAMPLES

54       None.
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APPLICATION USAGE

57       For functions that allocate memory as if by malloc(),  the  application
58       should  release  such memory when it is no longer required by a call to
59       free().  For strdup() and strndup(), this is the return value.
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61       Implementations are free to malloc() a buffer containing either (size +
62       1)  bytes  or  (strnlen(  s,  size) + 1) bytes. Applications should not
63       assume that strndup() will allocate (size + 1) bytes when strlen( s) is
64       smaller than size.
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RATIONALE

67       None.
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FUTURE DIRECTIONS

70       None.
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SEE ALSO

73       free(), wcsdup()
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75       The Base Definitions volume of POSIX.1‐2017, <string.h>
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78       Portions  of  this text are reprinted and reproduced in electronic form
79       from IEEE Std 1003.1-2017, Standard for Information Technology --  Por‐
80       table  Operating System Interface (POSIX), The Open Group Base Specifi‐
81       cations Issue 7, 2018 Edition, Copyright (C) 2018 by the  Institute  of
82       Electrical  and  Electronics Engineers, Inc and The Open Group.  In the
83       event of any discrepancy between this version and the original IEEE and
84       The  Open Group Standard, the original IEEE and The Open Group Standard
85       is the referee document. The original Standard can be  obtained  online
86       at http://www.opengroup.org/unix/online.html .
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88       Any  typographical  or  formatting  errors that appear in this page are
89       most likely to have been introduced during the conversion of the source
90       files  to  man page format. To report such errors, see https://www.ker
91       nel.org/doc/man-pages/reporting_bugs.html .
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95IEEE/The Open Group                  2017                           STRDUP(3P)
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