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46 .\" Copyright 2014 Garrett D'Amore <garrett@damore.org>
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49 .TH CTYPE 3C "Aug 20, 2019"
50 .SH NAME
51 ctype, isalpha, isalnum, isascii, isblank, iscntrl, isdigit, islower,
52 isprint, isspace, isupper, ispunct, isgraph, isxdigit, isalpha_l,
53 isalnum_l, isblank_l, iscntrl_l, isdigit_l, islower_l, isprint_l,
54 isspace_l, isupper_l, ispunct_l, isgraph_l, isxdigit_l \- character handling
55 .SH SYNOPSIS
56 .nf
57 #include <ctype.h>
58
59 \fBint\fR \fBisalpha\fR(\fBint\fR \fIc\fR);
60 .fi
61 .LP
62 .nf
63 \fBint\fR \fBisalnum\fR(\fBint\fR \fIc\fR);
64 .fi
65 .LP
66 .nf
67 \fBint\fR \fBisascii\fR(\fBint\fR \fIc\fR);
68 .fi
69 .LP
70 .nf
71 \fBint\fR \fBisblank\fR(\fBint\fR \fIc\fR);
72 .fi
73 .LP
74 .nf
75 \fBint\fR \fBiscntrl\fR(\fBint\fR \fIc\fR);
76 .fi
77 .LP
78 .nf
79 \fBint\fR \fBisdigit\fR(\fBint\fR \fIc\fR);
80 .fi
81 .LP
82 .nf
83 \fBint\fR \fBisgraph\fR(\fBint\fR \fIc\fR);
84 .fi
85 .LP
86 .nf
87 \fBint\fR \fBislower\fR(\fBint\fR \fIc\fR);
88 .fi
89 .LP
90 .nf
91 \fBint\fR \fBisprint\fR(\fBint\fR \fIc\fR);
92 .fi
93 .LP
94 .nf
95 \fBint\fR \fBispunct\fR(\fBint\fR \fIc\fR);
96 .fi
97 .LP
98 .nf
99 \fBint\fR \fBisspace\fR(\fBint\fR \fIc\fR);
100 .fi
101 .LP
102 .nf
103 \fBint\fR \fBisupper\fR(\fBint\fR \fIc\fR);
104 .fi
105 .LP
106 .nf
107 \fBint\fR \fBisxdigit\fR(\fBint\fR \fIc\fR);
108 .fi
109 .LP
110 .nf
111 \fBint\fR \fBisalpha_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
112 .fi
113 .LP
114 .nf
115 \fBint\fR \fBisalnum_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
116 .fi
117 .LP
118 .nf
119 \fBint\fR \fBisblank_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
120 .fi
121 .LP
122 .nf
123 \fBint\fR \fBiscntrl_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
124 .fi
125 .LP
126 .nf
127 \fBint\fR \fBisdigit_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
128 .fi
129 .LP
130 .nf
131 \fBint\fR \fBisgraph_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
132 .fi
133 .LP
134 .nf
135 \fBint\fR \fBislower_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
136 .fi
137 .LP
138 .nf
139 \fBint\fR \fBisprint_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
140 .fi
141 .LP
142 .nf
143 \fBint\fR \fBispunct_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
144 .fi
145 .LP
146 .nf
147 \fBint\fR \fBisspace_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
148 .fi
149 .LP
150 .nf
151 \fBint\fR \fBisupper_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
152 .fi
153 .LP
154 .nf
155 \fBint\fR \fBisxdigit_l\fR(\fBint\fR \fIc\fR, \fBlocale_t\fR \fIloc\fR);
156 .fi
157 .SH DESCRIPTION
158 These functions classify character-coded integer values. Each is a
159 predicate returning non-zero for true, \fB0\fR for false. The behavior
160 of these macros, except \fBisascii()\fR, is affected by the current
161 locale (see \fBsetlocale\fR(3C) and \fBuselocale\fR(3C)). To modify
162 the behavior, change the \fBLC_TYPE\fR category in \fBsetlocale()\fR, that is,
163 \fBsetlocale(\fR\fBLC_CTYPE\fR, \fInewlocale\fR). In the "C" locale,
164 or in a locale where character type information is not defined,
165 characters are classified according to the rules of the \fBUS-ASCII\fR
166 7-bit coded character set.
167 .LP
168 The functions \fBisalnum_l()\fR, \fBisalpha_l()\fR, \fBisblank_l()\fR,
169 \fBiscntrl_l\fR, \fBisdigit_l()\fR, \fBisgraph_l()\fR,
170 \fBislower_l()\fR, \fBisprint_l()\fR, \fBispunct_l()\fR,
171 \fBisspace_l()\fR, \fBisupper_l()\fR, and \fBisxdigit_l()\fR all behave
172 identically to their counterparts without the '\fB_l\fR' prefix, except
173 that instead of acting on the current locale, they perform the test on
174 the locale specified in the argument \fIloc\fR.
175 .LP
176 The \fBisascii()\fR macro is defined on all integer values. The rest are
177 defined only where the argument is an \fBint\fR, the value of which is
178 representable as an \fBunsigned char\fR, or \fBEOF\fR, which is defined by the
179 <\fBstdio.h\fR> header and represents end-of-file.
180 .sp
181 .ne 2
182 .na
183 \fBisalpha()\fR
184 .ad
185 .RS 13n
186 Tests for any character for which \fBisupper()\fR or \fBislower()\fR is true,
187 or any character that is one of the current locale-defined set of characters
188 for which none of \fBiscntrl()\fR, \fBisdigit()\fR, \fBispunct()\fR, or
189 \fBisspace()\fR is true. In "C" locale, \fBisalpha()\fR returns true only for
190 the characters for which \fBisupper()\fR or \fBislower()\fR is true.
191 .RE
192
193 .sp
194 .ne 2
195 .na
196 \fBisalnum()\fR
197 .ad
198 .RS 13n
199 Tests for any character for which \fBisalpha()\fR or \fBisdigit()\fR is true
200 (letter or digit).
201 .RE
202
203 .sp
204 .ne 2
205 .na
206 \fBisascii()\fR
207 .ad
208 .RS 13n
209 Tests for any ASCII character, code between \fB0\fR and \fB0177\fR inclusive.
210 .RE
211
212 .sp
213 .ne 2
214 .na
215 \fBisblank()\fR
216 .ad
217 .RS 13n
218 Tests whether \fIc\fR is a character of class blank in the current locale. This
219 macro/function is not available to applications conforming to standards prior
220 to SUSv3. See \fBstandards\fR(5)
221 .RE
222
223 .sp
224 .ne 2
225 .na
226 \fBiscntrl()\fR
227 .ad
228 .RS 13n
229 Tests for any ``control character'' as defined by the character set.
230 .RE
231
232 .sp
233 .ne 2
234 .na
235 \fBisdigit()\fR
236 .ad
237 .RS 13n
238 Tests for any decimal-digit character.
239 .RE
240
241 .sp
242 .ne 2
243 .na
244 \fBisgraph()\fR
245 .ad
246 .RS 13n
247 Tests for any character for which \fBisalnum()\fR and \fBispunct()\fR are true,
248 or any character in the current locale-defined "graph" class which is neither a
249 space ("\|") nor a character for which \fBiscntrl()\fR is true.
250 .RE
251
252 .sp
253 .ne 2
254 .na
255 \fBislower()\fR
256 .ad
257 .RS 13n
258 Tests for any character that is a lower-case letter or is one of the current
259 locale-defined set of characters for which none of \fBiscntrl()\fR,
260 \fBisdigit()\fR, \fBispunct()\fR, \fBisspace()\fR, or \fBisupper()\fR is true.
261 In the "C" locale, \fBislower()\fR returns true only for the characters defined
262 as lower-case \fBASCII\fR characters.
263 .RE
264
265 .sp
266 .ne 2
267 .na
268 \fBisprint()\fR
269 .ad
270 .RS 13n
271 Tests for any character for which \fBiscntrl()\fR is false, and
272 \fBisalnum()\fR, \fBisgraph()\fR, \fBispunct()\fR, the space character ("\|"),
273 and the characters in the current locale-defined "print" class are true.
274 .RE
275
276 .sp
277 .ne 2
278 .na
279 \fBispunct()\fR
280 .ad
281 .RS 13n
282 Tests for any printing character which is neither a space ("\|") nor a
283 character for which \fBisalnum()\fR or \fBiscntrl()\fR is true.
284 .RE
285
286 .sp
287 .ne 2
288 .na
289 \fBisspace()\fR
290 .ad
291 .RS 13n
292 Tests for any space, tab, carriage-return, newline, vertical-tab or form-feed
293 (standard white-space characters) or for one of the current locale-defined set
294 of characters for which \fBisalnum()\fR is false. In the "C" locale,
295 \fBisspace()\fR returns true only for the standard white-space characters.
296 .RE
297
298 .sp
299 .ne 2
300 .na
301 \fBisupper()\fR
302 .ad
303 .RS 13n
304 Tests for any character that is an upper-case letter or is one of the current
305 locale-defined set of characters for which none of \fBiscntrl()\fR,
306 \fBisdigit()\fR, \fBispunct()\fR, \fBisspace()\fR, or \fBislower()\fR is true.
307 In the "C" locale, \fBisupper()\fR returns true only for the characters defined
308 as upper-case \fBASCII\fR characters.
309 .RE
310
311 .sp
312 .ne 2
313 .na
314 \fBisxdigit()\fR
315 .ad
316 .RS 14n
317 Tests for any hexadecimal-digit character (\fB[0\(mi9]\fR, \fB[A\(miF]\fR, or
318 \fB[a\(mif]\fR or the current locale-defined sets of characters representing
319 the hexadecimal digits \fB10\fR to \fB15\fR inclusive). In the "C" locale, only
320 .sp
321 .in +2
322 .nf
323 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f
324 .fi
325 .in -2
326
327 are included.
328 .RE
329
330 .SH RETURN VALUES
331 If the argument to any of the character handling macros is not in the domain of
332 the function, the result is undefined. Otherwise, the macro or function returns
333 non-zero if the classification is \fBTRUE\fR and \fB0\fR if the classification
334 is \fBFALSE\fR.
335 .SH ATTRIBUTES
336 See \fBattributes\fR(5) for descriptions of the following attributes:
337 .TS
338 box;
339 c | c
340 l | l .
341 ATTRIBUTE TYPE ATTRIBUTE VALUE
342 _
343 CSI Enabled
344 _
345 Interface Stability Standard
346 _
347 MT-Level MT-Safe
348 .TE
349
350 .SH SEE ALSO
351 \fBnewlocale\fR(3C), \fBsetlocale\fR(3C), \fBuselocale\fR(3C),
352 \fBstdio\fR(3C), \fBascii\fR(5), \fBenviron\fR(5),
353 \fBstandards\fR(5)