Ctype.h

Name
: Character Operations -

Detailed Description
These functions perform various operations on characters.
 * 1) include 

Character classification routines
These functions perform character classification. They return true or false status depending whether the character passed to the function falls into the function's classification (i.e. isdigit returns true if its argument is any value '0' though '9', inclusive.) int isalnum (int __c) __ATTR_CONST__ int isalpha (int __c) __ATTR_CONST__ int isascii (int __c) __ATTR_CONST__ int isblank (int __c) __ATTR_CONST__ int iscntrl (int __c) __ATTR_CONST__ int isdigit (int __c) __ATTR_CONST__ int isgraph (int __c) __ATTR_CONST__ int islower (int __c) __ATTR_CONST__ int isprint (int __c) __ATTR_CONST__ int ispunct (int __c) __ATTR_CONST__ int isspace (int __c) __ATTR_CONST__ int isupper (int __c) __ATTR_CONST__ int isxdigit (int __c) __ATTR_CONST__

Character convertion routines
If c is not an unsigned char value, or EOF, the behaviour of these functions is undefined. int toascii (int __c) __ATTR_CONST__ int tolower (int __c) __ATTR_CONST__ int toupper (int __c) __ATTR_CONST__

int isalnum (int __c)
Checks for an alphanumeric character. It is equivalent to (isalpha(c) || isdigit(c)).

int isalpha (int __c)
Checks for an alphabetic character. It is equivalent to (isupper(c) || islower(c)).

int isascii (int __c)
Checks whether c is a 7-bit unsigned char value that fits into the ASCII character set.

int isblank (int __c)
Checks for a blank character, that is, a space or a tab.

int iscntrl (int __c)
Checks for a control character.

int isdigit (int __c)
Checks for a digit (0 through 9).

int isgraph (int __c)
Checks for any printable character except space.

int islower (int __c)
Checks for a lower-case character.

int isprint (int __c)
Checks for any printable character including space.

int ispunct (int __c)
Checks for any printable character which is not a space or an alphanumeric character.

int isspace (int __c)
Checks for white-space characters. For the avr-libc library, these are: space, form-feed ('\f'), newline ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v').

int isupper (int __c)
Checks for an uppercase letter.

int isxdigit (int __c)
Checks for a hexadecimal digits, i.e. one of 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F.

int toascii (int __c)
Converts c to a 7-bit unsigned char value that fits into the ASCII character set, by clearing the high-order bits.

Warning: Many people will be unhappy if you use this function. This function will convert accented letters into random characters.

int tolower (int __c)
Converts the letter c to lower case, if possible.

int toupper (int __c)
Converts the letter c to upper case, if possible.