1 
int isalnum(int c); 
!=0 if c is an alphanumeric character
in range 'A''Z', 'a''z', '0''9' 
2 
int isalpha(int c); 
!=0 if c is an alphabetic character is range 'A''Z',
'a''z' 
3 
int iscntrl(int c); 
!=0 if c is a control character in range 0x00x1F
or 0x7F 
4 
int isdigit(int c); 
!=0 if c is a digit in range '0''9' 
5 
int isgraph(int c); 
!=0 if c is a printable character (excluding space)
in range 0x210x7E 
6 
int islower(int c); 
!=0 if c is lower case letter in range 'a''z' 
7 
int isprint(int c); 
!=0 if c is a printable character in range 0x200x7E 
8 
int ispunct(int c); 
!=0 if c is a punctuation character in range 0x210x2F,
0x3A0X40, 0X5B0X60, 0X7B0X7E 
9 
int isspace(int c); 
!=0 if c is a white space character in range 0x90xD
or 0x20 
10 
int isupper(int c); 
!=0 if c is upper case letter in range 'A''Z' 
11 
int isxdigit(int c); 
!=0 if c is a hexadecimal digit in range '0''9',
'A''F', 'a''f' 
12 
int tolower(int c); 
return lower case value of character c in range 'a''z' 
13 
int toupper(int c); 
return upper case value of character c in range 'A''Z' 


