Each of these routines tests a specified byte of a multibyte character for satisfaction of a condition. Except where specified otherwise, the test result depends on the multibyte code page currently in use.
Note By definition, the ASCII character set is a subset of all multibyte-character sets. For example, the Japanese katakana character set includes ASCII as well as non-ASCII characters.
The manifest constants in the following table are defined in CTYPE.H:
Multibyte-Character Byte-Classification Routines
| Routine | Byte Test Condition |
| isleadbyte | Lead byte; test result depends on LC_CTYPE category setting of current locale |
| _ismbbalnum | isalnum || _ismbbkalnum |
| _ismbbalpha | isalpha || _ismbbkalnum |
| _ismbbgraph | Same as _ismbbprint, but _ismbbgraph does not include the space character (0x20) |
| _ismbbkalnum | Non-ASCII text symbol other than punctuation. For example, in code page 932 only, _ismbbkalnum tests for katakana alphanumeric |
| _ismbbkana | Katakana (0xA1 – 0xDF), code page 932 only |
| _ismbbkprint | Non-ASCII text or non-ASCII punctuation symbol. For example, in code page 932 only, _ismbbkprint tests for katakana alphanumeric or katakana punctuation (range: 0xA1 – 0xDF). |
| _ismbbkpunct | Non-ASCII punctuation. For example, in code page 932 only, _ismbbkpunct tests for katakana punctuation. |
| _ismbblead | First byte of multibyte character. For example, in code page 932 only, valid ranges are 0x81 – 0x9F, 0xE0 – 0xFC. |
| _ismbbprint | isprint || _ismbbkprint. ismbbprint includes the space character (0x20) |
| _ismbbpunct | ispunct || _ismbbkpunct |
| _ismbbtrail | Second byte of multibyte character. For example, in code page 932 only, valid ranges are 0x40 – 0x7E, 0x80 – 0xEC. |
| _ismbslead | Lead byte (in string context) |
| _ismbstrail | Trail byte (in string context) |
| _mbbtype | Return byte type based on previous byte |
| _mbsbtype | Return type of byte within string |
The MB_LEN_MAX macro, defined in LIMITS.H, expands to the maximum length in bytes that any multibyte character can have. MB_CUR_MAX, defined in STDLIB.H, expands to the maximum length in bytes of any multibyte character in the current locale.