1 .TH CTYPE 3
2 .SH NAME
3 isalpha, isupper, islower, isdigit, isxdigit, isalnum, isspace, ispunct, isprint, isgraph, iscntrl, isascii, toascii, _toupper, _tolower, toupper, tolower \- ASCII character classification
4 .SH SYNOPSIS
5 .B #include <u.h>
6 .br
7 .B #include <libc.h>
8 .br
9 .B #include <ctype.h>
10 .PP
11 .if t .2C
12 .B isalpha(c)
13 .PP
14 .B isupper(c)
15 .PP
16 .B islower(c)
17 .PP
18 .B isdigit(c)
19 .PP
20 .B isxdigit(c)
21 .PP
22 .B isalnum(c)
23 .PP
24 .B isspace(c)
25 .PP
26 .B ispunct(c)
27 .PP
28 .B isprint(c)
29 .PP
30 .B isgraph(c)
31 .PP
32 .B iscntrl(c)
33 .PP
34 .B isascii(c)
35 .PP
36 .B _toupper(c)
37 .PP
38 .B _tolower(c)
39 .PP
40 .B toupper(c)
41 .PP
42 .B tolower(c)
43 .PP
44 .B toascii(c)
45 .if t .1C
46 .SH DESCRIPTION
47 These macros classify
48 .SM ASCII\c
49 -coded integer values
50 by table lookup.
51 Each is a predicate returning nonzero for true,
52 zero for false.
53 .I Isascii
54 is defined on all integer values; the rest
55 are defined only where
56 .I isascii
57 is true and on the single non-\c
58 .SM ASCII
59 value
60 .BR EOF ;
61 see
62 .IR fopen (3).
63 .TP "\w'isalnum  'u"
64 .I isalpha
65 .I c
66 is a letter, a\-z or A\-Z
67 .TP
68 .I isupper
69 .I c
70 is an upper case letter, A\-Z
71 .TP
72 .I islower
73 .I c
74 is a lower case letter, a\-z
75 .TP
76 .I isdigit
77 .I c
78 is a digit, 0\-9
79 .TP
80 .I isxdigit
81 .I c
82 is a hexadecimal digit, 0\-9 or a\-f or A\-F
83 .TP
84 .I isalnum
85 .I c
86 is an alphanumeric character, a\-z or A\-Z or 0\-9
87 .TP
88 .I isspace
89 .I c
90 is a space, horizontal tab, newline, vertical tab, formfeed, or carriage return
91 (0x20, 0x9, 0xA, 0xB, 0xC, 0xD)
92 .TP
93 .I ispunct
94 .I c
95 is a punctuation character
96 (one of
97 .L
98 !"#$%&'()*+,-./:;<=>?@[\e]^_`{|}~\fR)
99 .TP
100 .I isprint
101 .I c
102 is a printing character, 0x20 (space)
103 through 0x7E (tilde) 
104 .TP
105 .I isgraph
106 .I c
107 is a visible printing character, 0x21 (exclamation) through 0x7E
108 (tilde)
109 .TP
110 .I iscntrl
111 .I c
112 is a delete character, 0x7F,
113 or ordinary control character, 0x0 through 0x1F
114 .TP
115 .I isascii
116 .I c
117 is an
118 .SM ASCII
119 character, 0x0 through 0x7F
120 .PP
121 .I Toascii
122 is not a classification macro;
123 it converts its argument to
124 .SM ASCII
125 range by
126 .IR and ing
127 with 0x7F.
128 .PP
129 If
130 .I c
131 is an upper case letter,
132 .I tolower
133 returns the lower case version of the character;
134 otherwise it returns the original character.
135 .I Toupper
136 is similar, returning the upper case version of a character
137 or the original character.
138 .I Tolower
139 and
140 .I toupper
141 are functions;
142 .I _tolower
143 and
144 .I _toupper
145 are corresponding macros which should only be used when it
146 is known that the argument is upper case or lower case, respectively.
147 .SH SOURCE
148 .TF /usr/local/plan9/src/libc/port/ctype.c
149 .TP
150 .B /sys/include/ctype.h
151 for the macros.
152 .TP
153 .B /usr/local/plan9/src/libc/port/ctype.c
154 for the tables.
155 .SH "SEE ALSO
156 .IR isalpharune (3)
157 .SH BUGS
158 These macros are
159 .SM ASCII \c
160 -centric.