Character Classification

Article
04/22/2008

Each of these routines tests a specified single-byte character, wide character, or multibyte character for satisfaction of a condition. (By definition, the ASCII character set between 0 and 127 are a subset of all multibyte-character sets. For example, Japanese katakana includes ASCII as well as non-ASCII characters.)

The test conditions are affected by the setting of the LC_CTYPE category setting of the locale; see setlocale for more information. The versions of these functions without the _l suffix use the current locale for this locale-dependent behavior; the versions with the _l suffix are identical except that they use the locale parameter passed in instead.

Generally these routines execute faster than tests you might write and should be favored over. For example, the following code executes slower than a call to isalpha(c):

if ((c >= 'A') && (c <= 'Z')) || ((c >= 'a') && (c <= 'z'))
    return TRUE;

Character-Classification Routines

Routine	Character test condition	.NET Framework equivalent
isalnum, iswalnum, _isalnum_l, _iswalnum_l, _ismbcalnum, _ismbcalnum_l, _ismbcalpha, _ismbcalpha_, _ismbcdigit, _ismbcdigit_l	Alphanumeric	System::Char::IsLetterOrDigit.
_ismbcalnum, _ismbcalnum_l, _ismbcalpha, _ismbcalpha_, _ismbcdigit, _ismbcdigit_l	Alphanumeric	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
isalpha, iswalpha, _isalpha_l, _iswalpha_l, _ismbcalnum, _ismbcalnum_l, _ismbcalpha, _ismbcalpha_, _ismbcdigit, _ismbcdigit_l	Alphabetic	System::Char::IsLetter
__isascii, iswascii	ASCII	System::Char::IsLetter
iscntrl, iswcntrl, _iscntrl_l, _iswcntrl_l	Control	System::Char::IsControl
__iscsym, __iswcsym, __iscsymf, __iswcsymf, _iscsym_l, _iswcsym_l, _iscsymf_l, _iswcsymf_l	Letter, underscore, or digit	System::Char::IsControl
__iscsym, __iswcsym, __iscsymf, __iswcsymf, _iscsym_l, _iswcsym_l, _iscsymf_l, _iswcsymf_l	Letter or underscore	System::Char::IsControl
isdigit, iswdigit, _isdigit_l, _iswdigit_l, _ismbcalnum, _ismbcalnum_l, _ismbcalpha, _ismbcalpha_, _ismbcdigit, _ismbcdigit_l	Decimal digit	System::Char::IsDigit
isgraph, iswgraph, _isgraph_l, _iswgraph_l, _ismbcgraph, _ismbcgraph_l, _ismbcprint, _ismbcprint_l, _ismbcpunct, _ismbcpunct_l, _ismbcspace, _ismbcspace_l	Printable other than space	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
islower, iswlower, _islower_l, _iswlower_l, _ismbclower, _ismbclower_l, _ismbcupper, _ismbcupper_l	Lowercase	System::Char::IsLower
_ismbchira, _ismbchira_l, _ismbckata, _ismbckata_l	Hiragana	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbchira, _ismbchira_l, _ismbckata, _ismbckata_l	Katakana	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbclegal, _ismbclegal_l, _ismbcsymbol, _ismbcsymbol_l	Legal multibyte character	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbcl0, _ismbcl0_l, _ismbcl1, _ismbcl1_l, _ismbcl2, _ismbcl2_l	Japan-level 0 multibyte character	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbcl0, _ismbcl0_l, _ismbcl1, _ismbcl1_l, _ismbcl2, _ismbcl2_l	Japan-level 1 multibyte character	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbcl0, _ismbcl0_l, _ismbcl1, _ismbcl1_l, _ismbcl2, _ismbcl2_l	Japan-level 2 multibyte character	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
_ismbclegal, _ismbclegal_l, _ismbcsymbol, _ismbcsymbol_l	Non-alphanumeric multibyte character	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
isprint, iswprint, _isprint_l, _iswprint_l, _ismbcgraph, _ismbcgraph_l, _ismbcprint, _ismbcprint_l, _ismbcpunct, _ismbcpunct_l, _ismbcspace, _ismbcspace_l	Printable	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
ispunct, iswpunct, _ispunct_l, _iswpunct_l, _ismbcgraph, _ismbcgraph_l, _ismbcprint, _ismbcprint_l, _ismbcpunct, _ismbcpunct_l, _ismbcspace, _ismbcspace_l	Punctuation	System::Char::IsPunctuation
isspace, iswspace, _isspace_l, _iswspace_l, _ismbcgraph, _ismbcgraph_l, _ismbcprint, _ismbcprint_l, _ismbcpunct, _ismbcpunct_l, _ismbcspace, _ismbcspace_l	White-space	System::Char::IsWhiteSpace
Isupper, iswupper, _ismbclower, _ismbclower_l, _ismbcupper, _ismbcupper_l	Uppercase	System::Char::IsUpper
_isctype, iswctype, _isctype_l, _iswctype_l	Property specified by desc argument	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.
isxdigit, iswxdigit, _isxdigit_l, _iswxdigit_l	Hexadecimal digit	System::Char::IsNumber
_mbclen, mblen, _mblen_l	Return length of valid multibyte character; result depends on LC_CTYPE category setting of current locale	Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

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