NAME
iscntrl —
control character test
LIBRARY
library “libc”
SYNOPSIS
#include
<ctype.h>
int
iscntrl(int
c);
int
iscntrl_l(int
c, locale_t
loc);
DESCRIPTION
Theiscntrl()
function tests for any control character. The value of the argument must be
representable as an unsigned char or the value of
EOF.
In the ASCII character set, this includes the following characters (with their numeric values shown in octal):
| 000 NUL | 001 SOH | 002 STX | 003 ETX | 004 EOT |
| 005 ENQ | 006 ACK | 007 BEL | 010 BS | 011 HT |
| 012 NL | 013 VT | 014 NP | 015 CR | 016 SO |
| 017 SI | 020 DLE | 021 DC1 | 022 DC2 | 023 DC3 |
| 024 DC4 | 025 NAK | 026 SYN | 027 ETB | 030 CAN |
| 031 EM | 032 SUB | 033 ESC | 034 FS | 035 GS |
| 036 RS | 037 US | 177 DEL |
The
iscntrl_l()
function takes an explicit locale argument, whereas the
iscntrl() function uses the current global or
per-thread locale.
RETURN VALUES
The iscntrl() function returns zero if the
character tests false and returns non-zero if the character tests true.
COMPATIBILITY
The 4.4BSD extension of accepting
arguments outside of the range of the unsigned char
type in locales with large character sets is considered obsolete and may not
be supported in future releases. The iswcntrl()
function should be used instead.
SEE ALSO
STANDARDS
The iscntrl() function conforms to
ISO/IEC 9899:1990 (“ISO C90”).
The iscntrl_l() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).