Classification function, the function library is ctype.h
Int isalpha (int CH) If CH is the letter ('A' - 'Z', 'A' - 'Z') Returns a non-0 value, otherwise returns 0
INT IsalNum (INT CH) If CH is a letter ('A' - 'Z', 'A' - 'Z') or Number ('0' - '9')
Return to a 0 value, otherwise returns 0
INT Isascii (int CH) If the CH is a character (0-127 in the ASCII code) returns a non-0 value, otherwise returns 0
INT ISCNTRL (INT CH) If CH is a waste character (0x7F) or normal control character (0x00-0x1f)
Return to a 0 value, otherwise returns 0
INT Isdigit (INT CH) If the CH is a number ('0' - '9') returns a non-0 value, otherwise returns 0
INT Isgraph (int CH) If the CH is a printable character (excluding space) (0x21-0X7E) returns a non-0 value, otherwise returns 0
INT Islower (INT CH) If the CH is lowercase letters ('A' - 'Z') returns a non-0 value, otherwise returns 0
INT Isprint (int CH) If the CH is a printable character (including the empty grid) (0x20-0x7e) Returns a non-0 value, otherwise returns 0
INT ISPUNCT (INT CH) Returns 0 value if the CH is the punctuation character (0x00-0x1f), otherwise returns 0
INT ISSPACE (INT CH) If CH is space (''), horizontal tab ('/ t'), carriage return ('/ r'),
Papermail wrap ('/ f'), vertical tab ('/ v'), newline character ('/ n')
Return to a 0 value, otherwise returns 0
Int IsUpper (int CH) If the CH is uppercase letters ('A' - 'Z') returns a non-0 value, otherwise returns 0
INT Isxdigit (INT CH) Returns non-zero value ('0' - '9', 'A' - 'f', 'A' - 'F') is returned to non-zero.
Otherwise returning 0
INT TOLOWER (INT CH) If CH is uppercase letters ('A' - 'Z') returns the corresponding lowercase letters ('A' - 'Z')
INT Toupper (int CH) Returns the corresponding uppercase letters ('A' - 'Z') in lowercase letters ('A' - 'Z')
