Manual Pages  — ISCNTRL

iscntrl – control character test

LIBRARY SYNOPSIS DESCRIPTION RETURN VALUES COMPATIBILITY SEE ALSO STANDARDS

Standard C Library (libc, -lc)

#include <ctype.h>

int
iscntrl(int c);

int
iscntrl_l(int c, locale_t loc);

The iscntrl() 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):

amp;000 NUL	001 SOH	002 STX	003 ETX	004 EOT
amp;005 ENQ	006 ACK	007 BEL	010 BS	011 HT
amp;012 NL	013 VT	014 NP	015 CR	016 SO
amp;017 SI	020 DLE	021 DC1	022 DC2	023 DC3
amp;024 DC4	025 NAK	026 SYN	027 ETB	030 CAN
amp;031 EM	032 SUB	033 ESC	034 FS	035 GS
amp;036 RS	037 US	177 DEL	amp;	amp;

The iscntrl_l() function takes an explicit locale argument, whereas the iscntrl() function uses the current global or per-thread locale.

The iscntrl() function returns zero if the character tests false and returns non-zero if the character tests true.

The BSD 4.4 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.

The iscntrl() function conforms to ISO/IEC 9899:1990 ("ISO C90"). The iscntrl_l() function conforms to IEEE Std 1003.1-2008 ("POSIX.1").