diff options
Diffstat (limited to 'manual')
| -rw-r--r-- | manual/charset.texi | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/manual/charset.texi b/manual/charset.texi index 9fd0166115..b638323fc2 100644 --- a/manual/charset.texi +++ b/manual/charset.texi @@ -1026,6 +1026,10 @@ stores in the pointer pointed to by @var{src} either a null pointer (if the NUL byte in the input string was reached) or the address of the byte following the last converted multibyte character. +Like @code{mbstowcs} the @var{dst} parameter may be a null pointer and +the function can be used to count the number of wide characters that +would be required. + @pindex wchar.h @code{mbsrtowcs} was introduced in @w{Amendment 1} to @w{ISO C90} and is declared in @file{wchar.h}. @@ -1101,10 +1105,11 @@ successfully converted. Except in the case of an encoding error the return value of the @code{wcsrtombs} function is the number of bytes in all the multibyte -character sequences stored in @var{dst}. Before returning, the state in -the object pointed to by @var{ps} (or the internal object in case -@var{ps} is a null pointer) is updated to reflect the state after the -last conversion. The state is the initial shift state in case the +character sequences which were or would have been (if @var{dst} was +not a null) stored in @var{dst}. Before returning, the state in the +object pointed to by @var{ps} (or the internal object in case @var{ps} +is a null pointer) is updated to reflect the state after the last +conversion. The state is the initial shift state in case the terminating NUL wide character was converted. @pindex wchar.h @@ -1131,6 +1136,10 @@ string @code{*@var{src}} need not be NUL-terminated. But if a NUL byte is found within the @var{nmc} first bytes of the string, the conversion stops there. +Like @code{mbstowcs} the @var{dst} parameter may be a null pointer and +the function can be used to count the number of wide characters that +would be required. + This function is a GNU extension. It is meant to work around the problems mentioned above. Now it is possible to convert a buffer with multibyte character text piece by piece without having to care about @@ -1465,6 +1474,12 @@ mbstowcs_alloc (const char *string) @} @end smallexample +If @var{wstring} is a null pointer then no output is written and the +conversion proceeds as above, and the result is returned. In practice +such behaviour is useful for calculating the exact number of wide +characters required to convert @var{string}. This behaviour of +accepting a null pointer for @var{wstring} is an @w{XPG4.2} extension +that is not specified in @w{ISO C} and is optional in @w{POSIX}. @end deftypefun @deftypefun size_t wcstombs (char *@var{string}, const wchar_t *@var{wstring}, size_t @var{size}) |