man3/ungetwc.3

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  10 .\" References consulted:
  11 .\"   GNU glibc-2 source code and manual
  12 .\"   Dinkumware C library reference http://www.dinkumware.com/
  13 .\"   OpenGroup's Single UNIX specification http://www.UNIX-systems.org/online.html
  14 .\"   ISO/IEC 9899:1999
  15 .\"
  16 .TH UNGETWC 3  2015-03-02 "GNU" "Linux Programmer's Manual"
  17 .SH NAME
  18 ungetwc \- push back a wide character onto a FILE stream
  19 .SH SYNOPSIS
  20 .nf
  21 .B #include <wchar.h>
  22 .sp
  23 .BI "wint_t ungetwc(wint_t " wc ", FILE *" stream );
  24 .fi
  25 .SH DESCRIPTION
  26 The
  27 .BR ungetwc ()
  28 function is the wide-character equivalent of the
  29 .BR ungetc (3)
  30 function.
  31 It pushes back a wide character onto
  32 .I stream
  33 and returns it.
  34 .PP
  35 If
  36 .I wc
  37 is
  38 .BR WEOF ,
  39 it returns
  40 .BR WEOF .
  41 If
  42 .I wc
  43 is an invalid wide character,
  44 it sets
  45 .IR errno
  46 to
  47 .B EILSEQ
  48 and returns
  49 .BR WEOF .
  50 .PP
  51 If
  52 .I wc
  53 is a valid wide character, it is pushed back onto the stream
  54 and thus becomes available for future wide-character read operations.
  55 The file-position indicator is decremented by one or more.
  56 The end-of-file
  57 indicator is cleared.
  58 The backing storage of the file is not affected.
  59 .PP
  60 Note:
  61 .I wc
  62 need not be the last wide-character read from the stream;
  63 it can be any other valid wide character.
  64 .PP
  65 If the implementation supports multiple push-back operations in a row, the
  66 pushed-back wide characters will be read in reverse order; however, only one
  67 level of push-back is guaranteed.
  68 .SH RETURN VALUE
  69 The
  70 .BR ungetwc ()
  71 function returns
  72 .IR wc
  73 when successful, or
  74 .B WEOF
  75 upon
  76 failure.
  77 .SH ATTRIBUTES
  78 For an explanation of the terms used in this section, see
  79 .BR attributes (7).
  80 .TS
  81 allbox;
  82 lb lb lb
  83 l l l.
  84 Interface       Attribute       Value
  85 T{
  86 .BR ungetwc ()
  87 T}      Thread safety   MT-Safe
  88 .TE
  89 .SH CONFORMING TO
  90 C99.
  91 .SH NOTES
  92 The behavior of
  93 .BR ungetwc ()
  94 depends on the
  95 .B LC_CTYPE
  96 category of the
  97 current locale.
  98 .SH SEE ALSO
  99 .BR fgetwc (3)