iscntrl

From cppreference.com
< c‎ | string‎ | byte
Defined in header <ctype.h>
int iscntrl( int ch );

Checks if the given character is a control character, i.e. codes 0x00-0x1F and 0x7F.

The behavior is undefined if the value of ch is not representable as unsigned char and is not equal to EOF.

Contents

[edit] Parameters

ch - character to classify

[edit] Return value

Non-zero value (true) if the character is a control character, 0 (false) otherwise.

[edit] Example

#include <stdio.h>
#include <ctype.h>
#include <limits.h>
 
int main(void)
{
    for (int ndx=0; ndx<=UCHAR_MAX; ndx++)
        if (iscntrl(ndx)) printf("0x%02x\n", ndx);
 
    return 0;
}

Output:

0x00
0x01
0x02
0x03
.
.
.
0x1f
0x7f

[edit] See also

checks if a wide character is a control character
(function)
C++ documentation for iscntrl
ASCII values
(hex)
characters

iscntrl
iswcntrl

isprint
iswprint

isspace
iswspace

isblank
iswblank

isgraph
iswgraph

ispunct
iswpunct

isalnum
iswalnum

isalpha
iswalpha

isupper
iswupper

islower
iswlower

isdigit
iswdigit

isxdigit
iswxdigit

0 - 8 0x00-0x08 control codes (NUL, etc.) ≠0 0 0 0 0 0 0 0 0 0 0 0
9 0x09 tab (\t) ≠0 0 ≠0 ≠0 0 0 0 0 0 0 0 0
10 - 13 0x0A-0x0D whitespaces (\n,\v,\f,\r) ≠0 0 ≠0 0 0 0 0 0 0 0 0 0
14 - 31 0x0E-0x1F control codes ≠0 0 0 0 0 0 0 0 0 0 0 0
32 0x20 space 0 ≠0 ≠0 ≠0 0 0 0 0 0 0 0 0
33 - 47 0x21-0x2F !"#$%&'()*+,-./ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
48 - 57 0x30-0x39 0123456789 0 ≠0 0 0 ≠0 0 ≠0 0 0 0 ≠0 ≠0
58 - 64 0x3a-0x40 :;<=>?@ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
65 - 70 0x41-0x46 ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0
71 - 90 0x47-0x5A GHIJKLMNOPQRSTUVWXYZ 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
91 - 96 0x5B-0x60 [\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
97 -102 0x61-0x66 abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0
103-122 0x67-0x7A ghijklmnopqrstuvwxyz 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
123-126 0x7B-0x7E {|}~ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
127 0x7F backspace character (DEL) ≠0 0 0 0 0 0 0 0 0 0 0 0