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mbsrtowcs(3C)

HP-UX 11i Version 3: February 2007
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NAME

mbsrtowcs() — convert a character string to a wide-character string (restartable)

SYNOPSIS

#include <wchar.h> size_t mbsrtowcs(wchar_t *__restrict dst, const char **__restrict src, size_t len, mbstate_t *__restrict ps);

DESCRIPTION

The mbsrtowcs() function converts a sequence of characters, beginning in the conversion state described by the object pointed to by ps, from the array indirectly pointed to by src into a sequence of corresponding wide-characters. If dst is not a null pointer, the converted characters are stored into the array pointed to by dst. Conversion continues up to and including a terminating null character, which is also stored. Conversion stops early in either of the following cases:

  • When a sequence of bytes is encountered that does not from a valid character.

  • When len codes have been stored into the array pointed to by dst (and dst is not a null pointer).

Each conversion takes place as if by a call to the mbrtowc() function.

If dst is not a null pointer, the pointer object pointed to by src is assigned either a null pointer (if conversion stopped due to reaching a terminating null character) or the address just past the last character converted (if any). If conversion stopped due to reaching a terminating null character, and if dst is not a null pointer, the resulting state described is the initial conversion state.

If ps is a null pointer, the mbsrtowcs() function uses its own internal mbstate_t object, which is initialized at program startup to the initial conversion state. Otherwise, the mbstate_t object pointed to by ps is used to completely describe the current conversion state of the associated character sequence. The implementation will behave as if no function defined in this specification calls mbsrtowcs().

APPLICATION USAGE

The prototype of this function is available to applications if they are:

a.

c99 conformant.

b.

Compiled with -D_XOPEN_SOURCE macro with a value >=500.

c.

Compiled with -D_POSIX_C_SOURCE macro with a value >= 200112.

EXTERNAL INFLUENCES

Environment Variables

The behavior of this function is affected by the LC_CTYPE category of the current locale.

RETURN VALUE

If the input conversion encounters a sequence of bytes that do not form a valid character, an encoding error occurs. In this case, the mbsrtowcs() function stores the value of the macro EILSEQ in errno and returns (size_t)-1; the conversion state is undefined. Otherwise, it returns the number of characters successfully converted, not including the terminating null (if any).

ERRORS

The mbsrtowcs() function may fail if:

EILSEQ

Invalid character sequence is detected.

EINVAL

ps points to an object that contains an invalid conversion state.

WARNINGS

With the exception of ASCII characters, the code values of wide characters (type of wchar_t) are specific to the effective locale specified by the LC_CTYPE environment variable. These values may not be compatible with values obtained by specifying other locales that are supported now, or which may be supported in the future. It is recommended that wide character constants and wide string literals (see the C Reference Manual) not be used, and that wide character code values not be stored in files or devices because future standards may dictate changes in the code value assignments of the wide characters. However, wide character constants and wide string literals corresponding to the characters of the ASCII code set can be safely used since their values are guaranteed to be the same as their ASCII code set values.

AUTHOR

mbsrtowcs() was developed by HP and Mitsubishi Electric Corporation.

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