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1.Is it possible to perform a sequence of operations on a wide-character stream so that its multibyte status will become shifted?
2. If you perform an operation on a narrow-character stream under a multi-byte locale and that operation stops in the middle of a compound character, will its multibyte status become shifted?
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I think you need to clarify your questions with more detail - it's not clear to me what you're asking.
If (s) is a stream then (s .tellg () .state ()) is its multibyte state. Using the codecvt facet of the stream’s locale, it is possible to test whether this state is shifted or not. Design an experiment where the expected result will be shifted.
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I would appreciate it if you could describe the problem in more detail, such as the functions involved, your needs, the purpose and so on. @Krzysztof Żelechowski
The functions involved are istream ::tellg (), streampos ::state () and codecvt ::unshift (). I am trying to store stream position in a file — but the shift state cannot be stored in a file, so I need to make sure there is no shift.
I suggest that you could use _lseek and _tell to check the offset. _lseek(fd,0, SEEK_END) can move to the end of the file. _tell(fd) can detect where it is. @Krzysztof Żelechowski
I meant in C++, not in POSIX.
You could try to use mbstate_t and mbsinit. They are in C runtime library. @Krzysztof Żelechowski
How can I use mbsinit to get a shifted state?
You could refer to this link about mbsinit. @Krzysztof Żelechowski