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25 .\" $FreeBSD: src/lib/libc/locale/mbrtowc.3,v 1.5 2004/06/30 19:32:41 ru Exp $

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27 .Dd April 8, 2004

28 .Dt MBRTOWC 3

29 .Os

30 .Sh NAME

31 .Nm mbrtowc ,

32 .Nm mbrtowc_l

33 .Nd "convert a character to a wide-character code (restartable)"

34 .Sh LIBRARY

35 .Lb libc

36 .Sh SYNOPSIS

37 .In wchar.h

38 .Ft size_t

39 .Fo mbrtowc

40 .Fa "wchar_t *restrict pwc"

41 .Fa "const char *restrict s"

42 .Fa "size_t n"

43 .Fa "mbstate_t *restrict ps"

44 .Fc

45 .In wchar.h

46 .In xlocale.h

47 .Ft size_t

48 .Fo mbrtowc_l

49 .Fa "wchar_t *restrict pwc"

50 .Fa "const char *restrict s"

51 .Fa "size_t n"

52 .Fa "mbstate_t *restrict ps"

53 .Fa "locale_t loc"

54 .Fc

55 .Sh DESCRIPTION

56 The

57 .Fn mbrtowc

58 function inspects at most

59 .Fa n

60 bytes, pointed to by

61 .Fa s ,

62 to determine the number of bytes needed to complete the next multibyte

63 character.

64 If a character can be completed, and

65 .Fa pwc

66 is not

67 .Dv NULL ,

68 the wide character which is represented by

69 .Fa s

70 is stored in the

71 .Vt wchar_t

72 it points to.

73 .Pp

74 If

75 .Fa s

76 is

77 .Dv NULL ,

78 .Fn mbrtowc

79 behaves as if

80 .Fa pwc

81 were

82 .Dv NULL ,

83 .Fa s

84 were an empty string

85 .Pq Qq ,

86 and

87 .Fa n

88 were 1.

89 .Pp

90 The

91 .Vt mbstate_t

92 argument,

93 .Fa ps ,

94 is used to keep track of the shift state.

95 If it is

96 .Dv NULL ,

97 .Fn mbrtowc

98 uses an internal, static

99 .Vt mbstate_t

100 object, which is initialized to the initial conversion state

101 at program startup.

102 .Pp

103 While the

104 .Fn mbrtowc

105 function uses the current locale, the

106 .Fn mbrtowc_l

107 function may be passed a locale directly. See

108 .Xr xlocale 3

109 for more information.

110 .Sh RETURN VALUES

111 The

112 .Fn mbrtowc

113 functions returns:

114 .Bl -tag -width indent

115 .It 0

116 The next

117 .Fa n

118 or fewer bytes

119 represent the null wide character

120 .Pq Li "L'\e0'" .

121 .It >0

122 The next

123 .Fa n

124 or fewer bytes

125 represent a valid character,

126 .Fn mbrtowc

127 returns the number of bytes used to complete the multibyte character.

128 .It Po Vt size_t Pc Ns \-2

129 The next

130 .Fa n

131 contribute to, but do not complete, a valid multibyte character sequence,

132 and all

133 .Fa n

134 bytes have been processed.

135 .It Po Vt size_t Pc Ns \-1

136 An encoding error has occurred.

137 The next

138 .Fa n

139 or fewer bytes do not contribute to a valid multibyte character.

140 .El

141 .Sh ERRORS

142 The

143 .Fn mbrtowc

144 function will fail if:

145 .Bl -tag -width Er

146 .It Bq Er EILSEQ

147 An invalid multibyte sequence was detected.

148 .It Bq Er EINVAL

149 The conversion state is invalid.

150 .El

151 .Sh SEE ALSO

152 .Xr mbtowc 3 ,

153 .Xr multibyte 3 ,

154 .Xr setlocale 3 ,

155 .Xr wcrtomb 3 ,

156 .Xr xlocale 3

157 .Sh STANDARDS

158 The

159 .Fn mbrtowc

160 function conforms to

161 .St -isoC-99 .