is, isw Routines
Visual Studio .NET 2003
Remarks
These routines test characters for specified conditions.
The is routines produce meaningful results for any integer argument from –1 (EOF) to UCHAR_MAX (0xFF), inclusive. The expected argument type is int.
Caution For the is routines, passing an argument of type char may yield unpredictable results. An SBCS or MBCS single-byte character of type char with a value greater than 0x7F is negative. If a char is passed, the compiler may convert the value to a signed int or a signed long. This value may be sign-extended by the compiler, with unexpected results.
The isw routines produce meaningful results for any integer value from – 1 (WEOF) to 0xFFFF, inclusive. The wint_t data type is defined in WCHAR.H as an unsigned short; it can hold any wide character or the wide-character end-of-file (WEOF) value.
For each of the is routines, the result of the test for the specified condition depends on the LC_CTYPE category setting of the current locale; see setlocale for more information. In the "C" locale, the test conditions for the is routines are as follows:
- isalnum
- Alphanumeric (A – Z, a – z, or 0 – 9).
- isalpha
- Alphabetic (A – Z or a – z).
- __isascii
- ASCII character (0x00 – 0x7F).
- iscntrl
- Control character (0x00 – 0x1F or 0x7F).
- __iscsym
- Letter, underscore, or digit.
- __iscsymf
- Letter or underscore.
- isdigit
- Decimal digit (0 – 9).
- isgraph
- Printable character except space ( ).
- islower
- Lowercase letter (a – z).
- isprint
- Printable character including space (0x20 – 0x7E).
- ispunct
- Punctuation character.
- isspace
- White-space character (0x09 – 0x0D or 0x20).
- isupper
- Uppercase letter (A – Z).
- isxdigit
- Hexadecimal digit (A – F, a – f, or 0 – 9).
For the isw routines, the result of the test for the specified condition is independent of locale. The test conditions for the isw functions are as follows:
- iswalnum
- iswalpha or iswdigit.
- iswalpha
- Any wide character that is one of an implementation-defined set for which none of iswcntrl, iswdigit, iswpunct, or iswspace is nonzero. iswalpha returns nonzero only for wide characters for which iswupper or iswlower is nonzero.
- iswascii
- Wide-character representation of ASCII character (0x0000 – 0x007F).
- iswcntrl
- Control wide character.
- iswctype
- Character has property specified by the desc argument. For each valid value of the desc argument of iswctype, there is an equivalent wide-character classification routine, as shown in the following table:
Equivalence of iswctype( c, desc ) to Other isw Testing Routines
Value of desc argument iswctype( c, desc ) equivalent _ALPHA iswalpha( c ) _ALPHA | _DIGIT iswalnum( c ) _CONTROL iswcntrl( c ) _DIGIT iswdigit( c ) _ALPHA | _DIGIT | _PUNCT iswgraph( c ) _LOWER iswlower( c ) _ALPHA | _BLANK | _DIGIT | _PUNCT iswprint( c ) _PUNCT iswpunct( c ) _SPACE iswspace( c ) _UPPER iswupper( c ) _HEX iswxdigit( c ) - iswdigit
- Wide character corresponding to a decimal-digit character.
- iswgraph
- Printable wide character except space wide character (L' ').
- iswlower
- Lowercase letter, or one of implementation-defined set of wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace is nonzero. iswlower returns nonzero only for wide characters that correspond to lowercase letters.
- iswprint
- Printable wide character, including space wide character (L' ').
- iswpunct
- Printable wide character that is neither space wide character (L' ') nor wide character for which iswalnum is nonzero.
- iswspace
- Wide character that corresponds to standard white-space character or is one of implementation-defined set of wide characters for which iswalnum is false. Standard white-space characters are: space (L' '), formfeed (L'\f'), newline (L'\n'), carriage return (L'\r'), horizontal tab (L'\t'), and vertical tab (L'\v').
- iswupper
- Wide character that is uppercase or is one of an implementation-defined set of wide characters for which none of iswcntrl, iswdigit, iswpunct, or iswspace is nonzero. iswupper returns nonzero only for wide characters that correspond to uppercase characters.
- iswxdigit
- Wide character that corresponds to a hexadecimal-digit character.
Example
// crt_isfam.c
/* This program tests all characters between 0x0
* and 0x7F, then displays each character with abbreviations
* for the character-type codes that apply.
*/
#include <stdio.h>
#include <ctype.h>
int main( void )
{
int ch;
for( ch = 0; ch <= 0x7F; ch++ )
{
printf( "%.2x ", ch );
printf( " %c", isprint( ch ) ? ch : ' ' );
printf( "%4s", isalnum( ch ) ? "AN" : "" );
printf( "%3s", isalpha( ch ) ? "A" : "" );
printf( "%3s", __isascii( ch ) ? "AS" : "" );
printf( "%3s", iscntrl( ch ) ? "C" : "" );
printf( "%3s", __iscsym( ch ) ? "CS " : "" );
printf( "%3s", __iscsymf( ch ) ? "CSF" : "" );
printf( "%3s", isdigit( ch ) ? "D" : "" );
printf( "%3s", isgraph( ch ) ? "G" : "" );
printf( "%3s", islower( ch ) ? "L" : "" );
printf( "%3s", ispunct( ch ) ? "PU" : "" );
printf( "%3s", isspace( ch ) ? "S" : "" );
printf( "%3s", isprint( ch ) ? "PR" : "" );
printf( "%3s", isupper( ch ) ? "U" : "" );
printf( "%3s", isxdigit( ch ) ? "X" : "" );
printf( ".\n" );
}
}
Output
00 AS C .
01 AS C .
02 AS C .
03 AS C .
04 AS C .
05 AS C .
06 AS C .
07 AS C .
08 AS C .
09 AS C S .
0a AS C S .
0b AS C S .
0c AS C S .
0d AS C S .
0e AS C .
0f AS C .
10 AS C .
11 AS C .
12 AS C .
13 AS C .
14 AS C .
15 AS C .
16 AS C .
17 AS C .
18 AS C .
19 AS C .
1a AS C .
1b AS C .
1c AS C .
1d AS C .
1e AS C .
1f AS C .
20 AS S PR .
21 ! AS G PU PR .
22 " AS G PU PR .
23 # AS G PU PR .
24 $ AS G PU PR .
25 % AS G PU PR .
26 & AS G PU PR .
27 ' AS G PU PR .
28 ( AS G PU PR .
29 ) AS G PU PR .
2a * AS G PU PR .
2b + AS G PU PR .
2c , AS G PU PR .
2d - AS G PU PR .
2e . AS G PU PR .
2f / AS G PU PR .
30 0 AN AS CS D G PR X.
31 1 AN AS CS D G PR X.
32 2 AN AS CS D G PR X.
33 3 AN AS CS D G PR X.
34 4 AN AS CS D G PR X.
35 5 AN AS CS D G PR X.
36 6 AN AS CS D G PR X.
37 7 AN AS CS D G PR X.
38 8 AN AS CS D G PR X.
39 9 AN AS CS D G PR X.
3a : AS G PU PR .
3b ; AS G PU PR .
3c < AS G PU PR .
3d = AS G PU PR .
3e > AS G PU PR .
3f ? AS G PU PR .
40 @ AS G PU PR .
41 A AN A AS CS CSF G PR U X.
42 B AN A AS CS CSF G PR U X.
43 C AN A AS CS CSF G PR U X.
44 D AN A AS CS CSF G PR U X.
45 E AN A AS CS CSF G PR U X.
46 F AN A AS CS CSF G PR U X.
47 G AN A AS CS CSF G PR U .
48 H AN A AS CS CSF G PR U .
49 I AN A AS CS CSF G PR U .
4a J AN A AS CS CSF G PR U .
4b K AN A AS CS CSF G PR U .
4c L AN A AS CS CSF G PR U .
4d M AN A AS CS CSF G PR U .
4e N AN A AS CS CSF G PR U .
4f O AN A AS CS CSF G PR U .
50 P AN A AS CS CSF G PR U .
51 Q AN A AS CS CSF G PR U .
52 R AN A AS CS CSF G PR U .
53 S AN A AS CS CSF G PR U .
54 T AN A AS CS CSF G PR U .
55 U AN A AS CS CSF G PR U .
56 V AN A AS CS CSF G PR U .
57 W AN A AS CS CSF G PR U .
58 X AN A AS CS CSF G PR U .
59 Y AN A AS CS CSF G PR U .
5a Z AN A AS CS CSF G PR U .
5b [ AS G PU PR .
5c \ AS G PU PR .
5d ] AS G PU PR .
5e ^ AS G PU PR .
5f _ AS CS CSF G PU PR .
60 ` AS G PU PR .
61 a AN A AS CS CSF G L PR X.
62 b AN A AS CS CSF G L PR X.
63 c AN A AS CS CSF G L PR X.
64 d AN A AS CS CSF G L PR X.
65 e AN A AS CS CSF G L PR X.
66 f AN A AS CS CSF G L PR X.
67 g AN A AS CS CSF G L PR .
68 h AN A AS CS CSF G L PR .
69 i AN A AS CS CSF G L PR .
6a j AN A AS CS CSF G L PR .
6b k AN A AS CS CSF G L PR .
6c l AN A AS CS CSF G L PR .
6d m AN A AS CS CSF G L PR .
6e n AN A AS CS CSF G L PR .
6f o AN A AS CS CSF G L PR .
70 p AN A AS CS CSF G L PR .
71 q AN A AS CS CSF G L PR .
72 r AN A AS CS CSF G L PR .
73 s AN A AS CS CSF G L PR .
74 t AN A AS CS CSF G L PR .
75 u AN A AS CS CSF G L PR .
76 v AN A AS CS CSF G L PR .
77 w AN A AS CS CSF G L PR .
78 x AN A AS CS CSF G L PR .
79 y AN A AS CS CSF G L PR .
7a z AN A AS CS CSF G L PR .
7b { AS G PU PR .
7c | AS G PU PR .
7d } AS G PU PR .
7e ~ AS G PU PR .
7f AS C .
See Also
Character Classification Routines | Locale Routines | setlocale | to Function Overview | Run-Time Routines and .NET Framework Equivalents
