# wcsrtombs

## 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



           wcsnrtombs, wcsrtombs — convert a wide-character string to a
           character string (restartable)
    


## SYNOPSIS



           #include <wchar.h>
    
           size_t wcsnrtombs(char *restrict _dst_ , const wchar_t **restrict _src_ ,
               size_t _nwc_ , size_t _len_ , mbstate_t *restrict _ps_);
           size_t wcsrtombs(char *restrict _dst_ , const wchar_t **restrict _src_ ,
               size_t _len_ , mbstate_t *restrict _ps_);
    


## DESCRIPTION



           For _wcsrtombs_(): The functionality described on this reference
           page is aligned with the ISO C standard. Any conflict between the
           requirements described here and the ISO C standard is
           unintentional. This volume of POSIX.1‐2017 defers to the ISO C
           standard.
    
           The _wcsrtombs_() function shall convert a sequence of wide
           characters from the array indirectly pointed to by _src_ into a
           sequence of corresponding characters, beginning in the conversion
           state described by the object pointed to by _ps_.  If _dst_ is not a
           null pointer, the converted characters shall then be stored into
           the array pointed to by _dst_.  Conversion continues up to and
           including a terminating null wide character, which shall also be
           stored. Conversion shall stop earlier in the following cases:
    
            *  When a code is reached that does not correspond to a valid
               character
    
            *  When the next character would exceed the limit of _len_ total
               bytes to be stored in the array pointed to by _dst_ (and _dst_ is
               not a null pointer)
    
           Each conversion shall take place as if by a call to the _wcrtomb_()
           function.
    
           If _dst_ is not a null pointer, the pointer object pointed to by _src_
           shall be assigned either a null pointer (if conversion stopped due
           to reaching a terminating null wide character) or the address just
           past the last wide character converted (if any). If conversion
           stopped due to reaching a terminating null wide character, the
           resulting state described shall be the initial conversion state.
    
           If _ps_ is a null pointer, the _wcsrtombs_() function shall use its
           own internal **mbstate_t** object, which is initialized at program
           start-up to the initial conversion state. Otherwise, the **mbstate_t**
           object pointed to by _ps_ shall be used to completely describe the
           current conversion state of the associated character sequence.
    
           The _wcsnrtombs_() and _wcsrtombs_() functions need not be thread-safe
           if called with a NULL _ps_ argument.
    
           The _wcsnrtombs_() function shall be equivalent to the _wcsrtombs_()
           function, except that the conversion is limited to the first _nwc_
           wide characters.
    
           The _wcsrtombs_() function shall not change the setting of _errno_ if
           successful.
    
           The behavior of these functions shall be affected by the _LC_CTYPE_
           category of the current locale.
    
           The implementation shall behave as if no function defined in
           System Interfaces volume of POSIX.1‐2017 calls these functions.
    


## RETURN VALUE



           If conversion stops because a code is reached that does not
           correspond to a valid character, an encoding error occurs. In this
           case, these functions shall store the value of the macro **[EILSEQ]**
           in _errno_ and return (**size_t**)-1; the conversion state is undefined.
           Otherwise, these functions shall return the number of bytes in the
           resulting character sequence, not including the terminating null
           (if any).
    


## ERRORS



           These functions shall fail if:
    
           **EILSEQ** A wide-character code does not correspond to a valid
                  character.
    
           These functions may fail if:
    
           **EINVAL** _ps_ points to an object that contains an invalid conversion
                  state.
    
           _The following sections are informative._
    


## EXAMPLES



           None.
    


## APPLICATION USAGE



           None.
    


## RATIONALE



           None.
    


## FUTURE DIRECTIONS



           None.
    


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