iscntrl

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.

Parameters

Return value

Non-zero value if the character is a control character, zero otherwise.

Example

#include <stdio.h>
#include <ctype.h>
#include <locale.h>
 
int main(void)
{
    unsigned char c = '\x94'; // the control code CCH in ISO-8859-1
    printf("In the default C locale, \\x94 is %sa control character\n",
           iscntrl(c) ? "" : "not " );
    setlocale(LC_ALL, "en_GB.iso88591");
    printf("In ISO-8859-1 locale, \\x94 is %sa control character\n",
           iscntrl(c) ? "" : "not " );
}

In the default C locale, \x94 is not a control character
In ISO-8859-1 locale, \x94 is a control character

References

• C11 standard (ISO/IEC 9899:2011):
  • 7.4.1.4 The iscntrl function (p: 201)
• C99 standard (ISO/IEC 9899:1999):
  • 7.4.1.4 The iscntrl function (p: 182)
• C89/C90 standard (ISO/IEC 9899:1990):
  • 4.3.1.3 The iscntrl function

See also