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<ctype.h>: Character Operations


Detailed Description

These functions perform various operations on characters.

 #include <ctype.h>


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__


Function Documentation

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.


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