ungetwc(3)

1ungetwc(3)                 Library Functions Manual                 ungetwc(3)
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NAME

6       ungetwc - push back a wide character onto a FILE stream
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <wchar.h>
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14       wint_t ungetwc(wint_t wc, FILE *stream);
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DESCRIPTION

17       The   ungetwc()  function  is  the  wide-character  equivalent  of  the
18       ungetc(3) function.  It pushes back a wide character  onto  stream  and
19       returns it.
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21       If wc is WEOF, it returns WEOF.  If wc is an invalid wide character, it
22       sets errno to EILSEQ and returns WEOF.
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24       If wc is a valid wide character, it is pushed back onto the stream  and
25       thus  becomes available for future wide-character read operations.  The
26       file-position indicator is decremented by one or more.  The end-of-file
27       indicator is cleared.  The backing storage of the file is not affected.
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29       Note:  wc  need not be the last wide-character read from the stream; it
30       can be any other valid wide character.
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32       If the implementation supports multiple push-back operations in a  row,
33       the pushed-back wide characters will be read in reverse order; however,
34       only one level of push-back is guaranteed.
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RETURN VALUE

37       The ungetwc() function returns wc when successful, or WEOF  upon  fail‐
38       ure.
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ATTRIBUTES

41       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
42       tributes(7).
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44       ┌────────────────────────────────────────────┬───────────────┬─────────┐
45       │Interface                                   │ Attribute     │ Value   │
46       ├────────────────────────────────────────────┼───────────────┼─────────┤
47       │ungetwc()                                   │ Thread safety │ MT-Safe │
48       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

51       C11, POSIX.1-2008.
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HISTORY

54       POSIX.1-2001, C99.
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NOTES

57       The behavior of ungetwc() depends  on  the  LC_CTYPE  category  of  the
58       current locale.
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