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  10 .TH CTYPE 3C "Jan 28, 2005"
  11 .SH NAME
  12 ctype, isalpha, isalnum, isascii, isblank, iscntrl, isdigit, islower, isprint,
  13 isspace, isupper, ispunct, isgraph, isxdigit \- character handling
  14 .SH SYNOPSIS
  15 .LP
  16 .nf
  17 #include <ctype.h>
  18 
  19 \fBint\fR \fBisalpha\fR(\fBint\fR \fIc\fR);
  20 .fi
  21 
  22 .LP
  23 .nf
  24 \fBint\fR \fBisalnum\fR(\fBint\fR \fIc\fR);
  25 .fi
  26 
  27 .LP
  28 .nf
  29 \fBint\fR \fBisascii\fR(\fBint\fR \fIc\fR);
  30 .fi
  31 
  32 .LP
  33 .nf
  34 \fBint\fR \fBisblank\fR(\fBint\fR \fIc\fR);
  35 .fi
  36 
  37 .LP
  38 .nf
  39 \fBint\fR \fBiscntrl\fR(\fBint\fR \fIc\fR);
  40 .fi
  41 
  42 .LP
  43 .nf
  44 \fBint\fR \fBisdigit\fR(\fBint\fR \fIc\fR);
  45 .fi
  46 
  47 .LP
  48 .nf
  49 \fBint\fR \fBisgraph\fR(\fBint\fR \fIc\fR);
  50 .fi
  51 
  52 .LP
  53 .nf
  54 \fBint\fR \fBislower\fR(\fBint\fR \fIc\fR);
  55 .fi
  56 
  57 .LP
  58 .nf
  59 \fBint\fR \fBisprint\fR(\fBint\fR \fIc\fR);
  60 .fi
  61 
  62 .LP
  63 .nf
  64 \fBint\fR \fBispunct\fR(\fBint\fR \fIc\fR);
  65 .fi
  66 
  67 .LP
  68 .nf
  69 \fBint\fR \fBisspace\fR(\fBint\fR \fIc\fR);
  70 .fi
  71 
  72 .LP
  73 .nf
  74 \fBint\fR \fBisupper\fR(\fBint\fR \fIc\fR);
  75 .fi
  76 
  77 .LP
  78 .nf
  79 \fBint\fR \fBisxdigit\fR(\fBint\fR \fIc\fR);
  80 .fi
  81 
  82 .SH DESCRIPTION
  83 .sp
  84 .LP
  85 These macros classify character-coded integer values. Each is a predicate
  86 returning non-zero for true, \fB0\fR for false. The behavior of these macros,
  87 except \fBisascii()\fR, is affected by the current locale (see
  88 \fBsetlocale\fR(3C)). To modify the behavior, change the \fBLC_TYPE\fR category
  89 in  \fBsetlocale()\fR, that is, \fBsetlocale(\fR\fBLC_CTYPE\fR,
  90 \fInewlocale\fR). In the "C" locale, or in a locale where character type
  91 information is not defined, characters are classified according to the rules of
  92 the \fBUS-ASCII\fR 7-bit coded character set.
  93 .sp
  94 .LP
  95 The \fBisascii()\fR macro is defined on all integer values. The rest are
  96 defined only where the argument is an \fBint\fR, the value of which is
  97 representable as an \fBunsigned char\fR, or \fBEOF\fR, which is defined by the
  98 <\fBstdio.h\fR> header and represents end-of-file.
  99 .sp
 100 .LP
 101 Functions exist for all the macros defined below. To get the function form, the
 102 macro name must be undefined (for example, \fB#undef isdigit\fR).
 103 .sp
 104 .LP
 105 For macros described with \fBDefault\fR and \fBStandard conforming\fR versions,
 106 standard-conforming behavior is provided for standard-conforming applications
 107 (see \fBstandards\fR(5)) and for applications that define
 108 \fB__XPG4_CHAR_CLASS__\fR before including <\fBctype.h\fR>.
 109 .SS "Default"
 110 .sp
 111 .ne 2
 112 .na
 113 \fB\fBisalpha()\fR\fR
 114 .ad
 115 .RS 13n
 116 Tests for any character for which \fBisupper()\fR or \fBislower()\fR is true.
 117 .RE
 118 
 119 .SS "Standard conforming"
 120 .sp
 121 .ne 2
 122 .na
 123 \fB\fBisalpha()\fR\fR
 124 .ad
 125 .RS 13n
 126 Tests for any character for which \fBisupper()\fR or \fBislower()\fR is true,
 127 or any character that is one of the current locale-defined set of characters
 128 for which none of \fBiscntrl()\fR, \fBisdigit()\fR, \fBispunct()\fR, or
 129 \fBisspace()\fR is true. In "C" locale, \fBisalpha()\fR returns true only for
 130 the characters for which \fBisupper()\fR or \fBislower()\fR is true.
 131 .RE
 132 
 133 .sp
 134 .ne 2
 135 .na
 136 \fB\fBisalnum()\fR\fR
 137 .ad
 138 .RS 13n
 139 Tests for any character for which \fBisalpha()\fR or \fBisdigit()\fR is true
 140 (letter or digit).
 141 .RE
 142 
 143 .sp
 144 .ne 2
 145 .na
 146 \fB\fBisascii()\fR\fR
 147 .ad
 148 .RS 13n
 149 Tests for any ASCII character, code between \fB0\fR and \fB0177\fR inclusive.
 150 .RE
 151 
 152 .sp
 153 .ne 2
 154 .na
 155 \fB\fBisblank()\fR\fR
 156 .ad
 157 .RS 13n
 158 Tests whether \fIc\fR is a character of class blank in the current locale. This
 159 macro/function is not available to applications conforming to standards prior
 160 to SUSv3. See \fBstandards\fR(5)
 161 .RE
 162 
 163 .sp
 164 .ne 2
 165 .na
 166 \fB\fBiscntrl()\fR\fR
 167 .ad
 168 .RS 13n
 169 Tests for any ``control character'' as defined by the character set.
 170 .RE
 171 
 172 .sp
 173 .ne 2
 174 .na
 175 \fB\fBisdigit()\fR\fR
 176 .ad
 177 .RS 13n
 178 Tests for any decimal-digit character.
 179 .RE
 180 
 181 .SS "Default"
 182 .sp
 183 .ne 2
 184 .na
 185 \fB\fBisgraph()\fR\fR
 186 .ad
 187 .RS 13n
 188 Tests for any character for which \fBispunct()\fR, \fBisupper()\fR,
 189 \fBislower()\fR, and \fBisdigit()\fR is true.
 190 .RE
 191 
 192 .SS "Standard conforming"
 193 .sp
 194 .ne 2
 195 .na
 196 \fB\fBisgraph()\fR\fR
 197 .ad
 198 .RS 13n
 199 Tests for any character for which \fBisalnum()\fR and \fBispunct()\fR are true,
 200 or any character in the current locale-defined "graph" class which is neither a
 201 space ("\|") nor a character for which \fBiscntrl()\fR is true.
 202 .RE
 203 
 204 .sp
 205 .ne 2
 206 .na
 207 \fB\fBislower()\fR\fR
 208 .ad
 209 .RS 13n
 210 Tests for any character that is a lower-case letter or is one of the current
 211 locale-defined set of characters for which none of \fBiscntrl()\fR,
 212 \fBisdigit()\fR, \fBispunct()\fR, \fBisspace()\fR, or \fBisupper()\fR is true.
 213 In the "C" locale, \fBislower()\fR returns true only for the characters defined
 214 as lower-case \fBASCII\fR characters.
 215 .RE
 216 
 217 .SS "Default"
 218 .sp
 219 .ne 2
 220 .na
 221 \fB\fBisprint()\fR\fR
 222 .ad
 223 .RS 13n
 224 Tests for any character for which \fBispunct()\fR, \fBisupper()\fR,
 225 \fBislower()\fR, \fBisdigit()\fR, and the space character ("\|") is true.
 226 .RE
 227 
 228 .SS "Standard conforming"
 229 .sp
 230 .ne 2
 231 .na
 232 \fB\fBisprint()\fR\fR
 233 .ad
 234 .RS 13n
 235 Tests for any character for which \fBiscntrl()\fR is false, and
 236 \fBisalnum()\fR, \fBisgraph()\fR, \fBispunct()\fR, the space character ("\|"),
 237 and the characters in the current locale-defined "print" class are true.
 238 .RE
 239 
 240 .sp
 241 .ne 2
 242 .na
 243 \fB\fBispunct()\fR\fR
 244 .ad
 245 .RS 13n
 246 Tests for any printing character which is neither a space ("\|") nor a
 247 character for which \fBisalnum()\fR or \fBiscntrl()\fR is true.
 248 .RE
 249 
 250 .sp
 251 .ne 2
 252 .na
 253 \fB\fBisspace()\fR\fR
 254 .ad
 255 .RS 13n
 256 Tests for any space, tab, carriage-return, newline, vertical-tab or form-feed
 257 (standard white-space characters) or for one of the current locale-defined set
 258 of characters for which \fBisalnum()\fR is false.  In the "C" locale,
 259 \fBisspace()\fR returns true only for the standard white-space characters.
 260 .RE
 261 
 262 .sp
 263 .ne 2
 264 .na
 265 \fB\fBisupper()\fR\fR
 266 .ad
 267 .RS 13n
 268 Tests for any character that is an upper-case letter or is one of the current
 269 locale-defined set of characters for which none of \fBiscntrl()\fR,
 270 \fBisdigit()\fR, \fBispunct()\fR, \fBisspace()\fR, or \fBislower()\fR is true.
 271 In the "C" locale, \fBisupper()\fR returns true only for the characters defined
 272 as upper-case \fBASCII\fR characters.
 273 .RE
 274 
 275 .SS "Default"
 276 .sp
 277 .ne 2
 278 .na
 279 \fB\fBisxdigit()\fR\fR
 280 .ad
 281 .RS 14n
 282 Tests for any hexadecimal-digit character (\fB[0\(mi9]\fR, \fB[A\(miF]\fR, or
 283 \fB[a\(mif]\fR).
 284 .RE
 285 
 286 .SS "Standard conforming"
 287 .sp
 288 .ne 2
 289 .na
 290 \fB\fBisxdigit()\fR\fR
 291 .ad
 292 .RS 14n
 293 Tests for any hexadecimal-digit character (\fB[0\(mi9]\fR, \fB[A\(miF]\fR, or
 294 \fB[a\(mif]\fR or the current locale-defined sets of characters representing
 295 the hexadecimal digits \fB10\fR to \fB15\fR inclusive). In the "C" locale, only
 296 .sp
 297 .in +2
 298 .nf
 299 0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f
 300 .fi
 301 .in -2
 302 
 303 are included.
 304 .RE
 305 
 306 .SH RETURN VALUES
 307 .sp
 308 .LP
 309 If the argument to any of the character handling macros is not in the domain of
 310 the function, the result is undefined. Otherwise, the macro or function returns
 311 non-zero if the classification is \fBTRUE\fR and \fB0\fR if the classification
 312 is \fBFALSE\fR.
 313 .SH USAGE
 314 .sp
 315 .LP
 316 These macros or functions can be used safely in multithreaded applications, as
 317 long as \fBsetlocale\fR(3C) is not being called to change the locale.
 318 .SH ATTRIBUTES
 319 .sp
 320 .LP
 321 See \fBattributes\fR(5) for descriptions of the following attributes:
 322 .sp
 323 
 324 .sp
 325 .TS
 326 box;
 327 l l
 328 l l .
 329 ATTRIBUTE TYPE  ATTRIBUTE VALUE
 330 CSI     Enabled
 331 Interface Stability     Standard
 332 MT-Level        MT-Safe with exceptions
 333 .TE
 334 
 335 .SH SEE ALSO
 336 .sp
 337 .LP
 338 \fBsetlocale\fR(3C), \fBstdio\fR(3C), \fBascii\fR(5), \fBenviron\fR(5),
 339 \fBstandards\fR(5)