Determine if an integer represents a control character.
int iscntrl( 
   int c 
);
int iswcntrl( 
   wint_t c 
);
int _iscntrl_l( 
   int c,
   _locale_t locale
);
int _iswcntrl_l( 
   wint_t c,
   _locale_t locale
);
Parameters
- c 
 Integer to test
- locale 
 The locale to use.
Return Value
Each of these routines returns nonzero if c is a particular representation of a control character. iscntrl returns a nonzero value if c is a control character (0x00 – 0x1F or 0x7F). iswcntrl returns a nonzero value if c is a control wide character. Each of these routines returns 0 if c does not satisfy the test condition.
When used with a debug CRT library, iscntrl will display a CRT assert if passed a parameter that is not EOF or in the range of 0 through 0xFF. When used with a debug CRT library, iscntrl will use the parameter as an index into an array, with undefined results if the parameter is not EOF or in the range of 0 through 0xFF.
The versions of these functions with the _l suffix are identical except that they use the locale parameter passed in instead of the current locale. For more information, see Locale.
Generic-Text Routine Mappings
| TCHAR.H routine | _UNICODE & _MBCS not defined | _MBCS defined | _UNICODE defined | 
|---|---|---|---|
| _istcntrl | iscntrl | iscntrl | iswcntrl | 
| _istcntrl_l | _iscntrl_l | _iscntrl_l | _iswcntrl_l | 
Requirements
| Routine | Required header | 
|---|---|
| iscntrl | <ctype.h> | 
| iswcntrl | <ctype.h> or <wchar.h> | 
| _iscntrl_l | <ctype.h> | 
| _iswcntrl_l | <ctype.h> or <wchar.h> | 
For additional compatibility information, see Compatibility in the Introduction.