The Open Group Base Specifications Issue 7
IEEE Std 1003.1-2008
Copyright © 2001-2008 The IEEE and The Open Group

NAME

iscntrl, iscntrl_l - test for a control character

SYNOPSIS

#include <ctype.h>

int iscntrl(int
c);

[CX] [Option Start] int iscntrl_l(int c, locale_t locale); [Option End]

DESCRIPTION

For iscntrl(): [CX] [Option Start]  The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard. [Option End]

The iscntrl() [CX] [Option Start]  and iscntrl_l() [Option End]  functions shall test whether c is a character of class cntrl in the current locale of the process, [CX] [Option Start]  or in the locale represented by locale, [Option End]  respectively; see XBD Locale .

The c argument is a type int, the value of which the application shall ensure is a character representable as an unsigned char or equal to the value of the macro EOF. If the argument has any other value, the behavior is undefined.

RETURN VALUE

The iscntrl() [CX] [Option Start]  and iscntrl_l() [Option End]  functions shall return non-zero if c is a control character; otherwise, they shall return 0.

ERRORS

The iscntrl_l() function may fail if:

[EINVAL]
[CX] [Option Start] locale is not a valid locale object handle. [Option End]

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

To ensure applications portability, especially across natural languages, only these functions and the functions in the reference pages listed in the SEE ALSO section should be used for character classification.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

isalnum , isalpha , isblank , isdigit , isgraph , islower , isprint , ispunct , isspace , isupper , isxdigit , setlocale , uselocale

XBD Locale , <ctype.h> , <locale.h>

CHANGE HISTORY

First released in Issue 1. Derived from Issue 1 of the SVID.

Issue 6

The normative text is updated to avoid use of the term "must" for application requirements.

Issue 7

The iscntrl_l() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 4.

End of informative text.

 

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