ctype.h

_tolower(a)   ((a)|0x20)

Converts an uppercase letter to its lowercase equivalent.

_toupper(a)   ((a)&0x5f)

Converts a lowercase letter to its uppercase equivalent.

isascii(a)   (0 ? isascii(a) : (unsigned)(a) < 128)

Checks whether a parameter is an ASCII character.

isalnum (int c)

int 

Checks whether a parameter is an alphabetic character or a decimal digit.

isalpha (int c)

int 

Checks whether a parameter is an alphabetic character.

isblank (int c)

int 

Checks whether a parameter is a blank character (space or tap).

iscntrl (int c)

int 

Checks whether a parameter is a control character. A control character is invisible and does not occupy a printing position on a display.

isdigit (int c)

int 

Checks whether a parameter is a decimal digit (0-9).

isgraph (int c)

int 

Checks whether a parameter is any printable character except the space character.

islower (int c)

int 

Checks whether a parameter is a lowercase letter.

isprint (int c)

int 

Checks whether a parameter is a printable character (including space).

ispunct (int c)

int 

Checks whether a parameter is a punctuation or special character.

isspace (int c)

int 

Checks whether a parameter is a space character.

isupper (int c)

int 

Checks whether a parameter is an uppercase letter.

isxdigit (int c)

int 

Checks whether a parameter is a hexadecimal digit.

tolower (int c)

int 

Converts an uppercase letter specified by c to its lowercase equivalent.

toupper (int c)

int 

Converts a lowercase letter specified by c to its uppercase equivalent.

isalnum_l (int c, locale_t locale)

int 

Checks whether a parameter is an alphabetic character or digit for the specified locale.

isalpha_l (int c, locale_t locale)

int 

Checks whether a parameter is an alphabetic character for the specified locale.

isblank_l (int c, locale_t locale)

int 

Checks whether a parameter is a blank character (including spaces and tabs) for the specified locale.

iscntrl_l (int c, locale_t locale)

int 

Checks whether a parameter is a control character for the specified locale.

isdigit_l (int c, locale_t locale)

int 

Checks whether a parameter is a decimal digit for the specified locale.

isgraph_l (int c, locale_t locale)

int 

Checks whether a parameter is any printable character except the space character for the specified locale.

islower_l (int c, locale_t locale)

int 

Checks whether a parameter is a character of lowercase letters for the specified locale.

isprint_l (int c, locale_t locale)

int 

Checks whether a parameter is a printable character (including space) for the specified locale. A printable character is visible and occupies a printing position on a display.

ispunct_l (int c, locale_t locale)

int 

Checks whether a parameter is a punctuation or special character for the specified locale.

isspace_l (int c, locale_t locale)

int 

Checks whether a parameter is a blank character for the specified locale.

isupper_l (int c, locale_t locale)

int 

Checks whether a parameter is a character of uppercase letters for the specified locale.

isxdigit_l (int c, locale_t locale)

int 

Checks whether a parameter is a hexadecimal digit for the specified locale.

tolower_l (int c, locale_t locale)

int 

Converts an upper letter specified by c to its lowercase equivalent for the specified locale.

toupper_l (int c, locale_t locale)

int 

Converts a lowercase letter specified by c to its uppercase equivalent for the specified locale.

toascii (int c)

int 

Converts a parameter of the integer type to an ASCII code.