2.2.1 is… Functions
Declarations:
int isalnum(intcharacter);character
int isalpha(int);character
int iscntrl(int);character
int isdigit(int);character
int isgraph(int);character
int islower(int);character
int isprint(int);character
int ispunct(int);character
int isspace(int);character
int isupper(int);character
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.
Conditions:
isalnum | a letter (A to Z or a to z) or a digit (0 to 9) |
isalpha | a letter (A to Z or a to z) |
iscntrl | any control character (0x00 to 0x1F or 0x7F) |
isdigit | a digit (0 to 9) |
isgraph | any printing character except for the space character (0x21 to 0x7E) |
islower | a lowercase letter (a to z) |
isprint | any printing character (0x20 to 0x7E) |
ispunct | any punctuation character (any printing character except for space character or isalnum) |
isspace | a whitespace character (space, tab, carriage return, new line, vertical tab, or formfeed) |
isupper | an uppercase letter (A to Z) |
isxdigit | a hexadecimal digit (0 to 9, A to F, or a to f) |