2.2.1 is… Functions


int isalnum(int character);
int isalpha(int
int iscntrl(int
int isdigit(int
int isgraph(int
int islower(int
int isprint(int
int ispunct(int
int isspace(int
int isupper(int
int isxdigit(int

The is… functions test the given character and return a nonzero (true) result if it satisfies the following conditions. If not, then 0 (false) is returned.


isalnuma letter (A to Z or a to z) or a digit (0 to 9)
isalphaa letter (A to Z or a to z)
iscntrlany control character (0x00 to 0x1F or 0x7F)
isdigita digit (0 to 9)
isgraphany printing character except for the space character (0x21 to 0x7E)
islowera lowercase letter (a to z)
isprintany printing character (0x20 to 0x7E)
ispunctany punctuation character (any printing character except for space character or isalnum)
isspacea whitespace character (space, tab, carriage return, new line, vertical tab, or formfeed)
isupperan uppercase letter (A to Z)
isxdigita hexadecimal digit (0 to 9, A to F, or a to f)