std::codecvt<InternT,ExternT,StateT>:: unshift, do_unshift
|
Defined in header
<locale>
|
||
|
public
:
result unshift
(
StateT
&
state, ExternT
*
to, ExternT
*
to_end,
|
(1) | |
|
protected
:
virtual
result do_unshift
(
StateT
&
state, ExternT
*
to, ExternT
*
to_end,
|
(2) | |
do_unshift
of the most derived class.
codecvt
facet is state-dependent, and
state
represents a conversion state that is not the initial shift state, writes the characters necessary to return to the initial shift state. The characters are written to a character array whose first element is pointed to by
to
. No more than
to_end
-
to
characters are written. The parameter
to_next
is updated to point one past the last character written.
Return value
A value of type std::codecvt_base::result , indicating the success status as follows:
ok
|
all necessary characters were written. state now represents initial shift state |
partial
|
not enough space in the output buffer. to_next == to_end |
error
|
an unspecified error has occurred |
noconv
|
the encoding is not state-dependent, no termination sequence necessary |
Notes
This function is called by std::basic_filebuf::close() and in other situations when finalizing a state-dependent multibyte character sequence.
Example
|
This section is incomplete
Reason: no example |
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 305 | C++98 |
std::
codecvt
<
wchar_t
,
char
,
std::
mbstate_t
>
::
do_unshift
was required not to write any character |
not required |
| LWG 380 | C++98 |
the meaning of returning
partial
was 'more characters need to
be supplied to complete termination', but no character is supplied |
corrected to indicating
insufficient buffer space |
| LWG 381 | C++98 |
state
was not required to be valid, and
error is returned if state is invalid |
state
is required to be valid, and
returning error indicates an error |
| LWG 664 | C++98 |
std::
codecvt
<
char
,
char
,
std::
mbstate_t
>
::
do_unshift
was required not to write any character |
not required |
| LWG 665 | C++98 |
std::
codecvt
<
char
,
char
,
std::
mbstate_t
>
::
do_unshift
was required to return noconv |
not required |
See also
|
converts a wide character to its multibyte representation, given state
(function) |
|
|
[virtual]
|
converts a string from
InternT
to
ExternT
, such as when writing to file
(virtual protected member function) |