Synopsis

(Mandatory) The relevant functions from <ctype.h> are defined to take an int argument where the expected value is either in the range of an unsigned char or is a negative value equivalent to EOF. The use of any other values results in undefined behaviour.

Enabled by default

Yes

Severity/Certainty

High/Low

Full description

Any value passed to a function in <ctype.h> shall be representable as an unsigned char or be the value EOF.

Coding standards

Code examples

The following code example fails the check and will give a warning:

#include <ctype.h>
#include "mc3_types.h"

bool_t f(uint8_t a) {
    return isalpha( 256 );
}

The following code example passes the check and will not give a warning about this issue:

#include <ctype.h>
#include <stdio.h>
#include "mc3_types.h"

bool_t f(uint8_t a) {
    return isdigit ( ( int32_t ) a )
        && isalpha ( ( int32_t ) 'b' )
        && islower( EOF );
}