### isalnum to isxdigit -- Test Integer Value

Format

>     #include <ctype.h>
>                                   /* test for:              */
>     int isalnum(int c);  /* alphanumeric character */
>     int isalpha(int c);  /* alphabetic character   */
>     int iscntrl(int c);  /* control character      */
>     int isdigit(int c);  /* decimal digit          */
>     int isgraph(int c);  /* printable character, excluding space */
>     int islower(int c);  /* lowercase character    */
>     int isprint(int c);  /* printable character, including space */
>     int ispunct(int c);  /* nonalphanumeric printable character, excluding space */
>     int isspace(int c);  /* whitespace character   */
>     int isupper(int c);  /* uppercase character    */
>     int isxdigit(int c); /* hexadecimal digit      */

Language Level: ANSI, POSIX, XPG4
These functions test a given integer value c to determine if it has a certain property as defined by the LC_CTYPE category of your current locale. The value of c must be representable as an unsigned char, or EOF.

The functions test for the following:

isalnum | Alphanumeric character (upper- or lowercase letter, or decimal digit), as defined in the locale source file in the alnum class of the LC_CTYPE category of the current locale.
isalpha | Alphabetic character, as defined in the locale source file in the alpha class of the LC_CTYPE category of the current locale.
iscntrl | Control character, as defined in the locale source file in the cntrl class of the LC_CTYPE category of the current locale.
isdigit | Decimal digit (0 through 9), as defined in the locale source file in the digit class of the LC_CTYPE category of the current locale.
isgraph | Printable character, excluding the space character, as defined in the locale source file in the graph class of the LC_CTYPE category of the current locale.
islower | Lowercase letter, as defined in the locale source file in the lower class of the LC_CTYPE category of the current locale.
isprint | Printable character, including the space character, as defined in the locale source file in the print class of the LC_CTYPE category of the current locale.
ispunct | Nonalphanumeric printable character, excluding the space character, as defined in the locale source file in the punct class of the LC_CTYPE category of the current locale.
isspace | White-space character, as defined in the locale source file in the space class of the LC_CTYPE category of the current locale.
isupper | Uppercase letter, as defined in the locale source file in the upper class of the LC_CTYPE category of the current locale.
isxdigit | Hexadecimal digit (0 through 9, a through f, or A through F), as defined in the locale source file in the xdigit class of the LC_CTYPE category of the current locale.

You can redefine any character class in the LC_CTYPE category of the current locale, with some restrictions.

Return Value
These functions return a nonzero value if the integer satisfies the test condition, or 0 if it does not.

Example

isascii -- Test Integer Values
_iscsym - _iscsymf -- Test Integer
iswalnum to iswxdigit -- Test Wide Integer Value
setlocale -- Set Locale
tolower - toupper -- Convert Character Case
_toascii -_tolower -_toupper -- Convert Character
<ctype.h>
LC_CTYPE Locale Category Source Definition