Character classes [C library]

These functions work on ASCII characters and can classify them as well as change between upper and lower case letters. More...

Functions
int	isalnum (int c)
	Tests if a character is an alphanumeric character.
int	isalpha (int c)
	Tests if a character is an alphabetic character.
int	isascii (int c)
	Tests if a character is an alphabetic character.
int	isblank (int c)
	Tests if a character is tabulator or space character.
int	iscntrl (int c)
	Tests if a character is an ASCII control character.
int	isdigit (int c)
	Tests if a character is a decimal digit character.
int	isgraph (int c)
	Tests if a character is a decimal digit character.
int	islower (int c)
	Tests if a character is a lowercase letter character.
int	isprint (int c)
	Tests if a character is a printable character.
int	ispunct (int c)
	Tests if a character is a punctuation character.
int	isspace (int c)
	Tests if a character is a whitespace character.
int	isupper (int c)
	Tests if a character is an uppercase letter.
int	isxdigit (int c)
	Tests if a character is a hexadecimal digit.
int	tolower (int c)
	Change characters to lowercase.
int	toupper (int c)
	Change characters to uppercase.

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Detailed Description

These functions work on ASCII characters and can classify them as well as change between upper and lower case letters.

To use these functions you have to include ctype.h.

The character classification is based on a class table, so these functions do a single table lookup. Such simple functions are good candidates for inlining. Therefore, if you define the

#define BLC_CTYPE_INLINE

symbol before you include the ctype.h header, then the functions will be inlined.

---

Function Documentation

int isalnum

(

int

c

)

Tests if a character is an alphanumeric character.

Parameters:

c

The character to test

Returns:

0 if the character is not alphanumeric, non-0 otherwise

int isalpha

(

int

c

)

Tests if a character is an alphabetic character.

Parameters:

c

The character to test

Returns:

0 if the character is not alphabetic, non-0 otherwise

int isascii

(

int

c

)

Tests if a character is an alphabetic character.

Parameters:

c

The character to test

Returns:

0 if the character is not alphabetic, non-0 otherwise

int isblank

(

int

c

)

Tests if a character is tabulator or space character.

Parameters:

c

The character to test

Returns:

0 if the character is neither tabulator nor space, non-0 otherwise

int iscntrl

(

int

c

)

Tests if a character is an ASCII control character.

Parameters:

c

The character to test

Returns:

0 if the character is not ASCII control, non-0 otherwise

int isdigit

(

int

c

)

Tests if a character is a decimal digit character.

Parameters:

c

The character to test

Returns:

0 if the character is not a decimal digit, non-0 otherwise

int isgraph

(

int

c

)

Tests if a character is a decimal digit character.

Parameters:

c

The character to test

Returns:

0 if the character is not a decimal digit, non-0 otherwise

int islower

(

int

c

)

Tests if a character is a lowercase letter character.

Parameters:

c

The character to test

Returns:

0 if the character is not a lowercase letter, non-0 otherwise

int isprint

(

int

c

)

Tests if a character is a printable character.

Parameters:

c

The character to test

Returns:

0 if the character is not a printable, non-0 if it is

int ispunct

(

int

c

)

Tests if a character is a punctuation character.

Parameters:

c

The character to test

Returns:

0 if the character is not punctuation, non-0 otherwise

int isspace

(

int

c

)

Tests if a character is a whitespace character.

Parameters:

c

The character to test

Returns:

0 if the character is not whitespace, non-0 otherwise

int isupper

(

int

c

)

Tests if a character is an uppercase letter.

Parameters:

c

The character to test

Returns:

0 if the character is not an upperces letter, non-0 otherwise

int isxdigit

(

int

c

)

Tests if a character is a hexadecimal digit.

Parameters:

c

The character to test

Returns:

0 if the character is not a hex digit, non-0 otherwise

int tolower

(

int

c

)

Change characters to lowercase.

This function changes uppercase letters to lowercase. The affected range is 'A' to 'Z'. All other values are returned verbatim.

Parameters:

c

The character to convert to lowercase

Returns:

The converted character

int toupper

(

int

c

)

Change characters to uppercase.

This function changes lowercase letters to uppercase. The affected range is 'a' to 'z'. All other values are returned verbatim.

Parameters:

c

The character to convert to uppercase

Returns:

The converted character