The <ctype.h> include file defines functions used in character classification. The functions defined in <ctype.h> are:
| isalnum | iscntrl | isprint | islower | tolower |
| isalpha | isdigit | ispunct | isupper | toupper |
| isblank | isgraph | isspace | isxdigit |
In extended mode, <ctype.h> also includes definitions for the following IBM C and C++ Compilers extensions:
| isascii | _iscsymf | _toascii | _tolower | _toupper |
| _iscsym |
For both OS/2 and Windows, in IBM C and C++ Compilers, the <ctype.h> functions are all implemented as macros.