MISRA C:2012  Rule-18.2:  (Required)			Subtraction between pointers shall only be applied to pointers that address elements of the same array

Example Code:

#pragma PRQA_MESSAGES_OFF 2982,2983

#include "misra.h"
#include "m3cmex.h"

extern int16_t rule_1802( void )
{
    int16_t   buf1[10];
    int16_t   buf2[10];
    int16_t * p1;
    int16_t * p2;
    int16_t * p3;
    int32_t   dx;

    p1 = buf1;
    p2 = buf2;
    dx = p2 - p1;                                               /* 2771 0488 */

    p3 = buf1;
    if (s16a > 0)
    {
        p3 = buf2;
    }

    dx = p3 - p1;                                               /* 2772 0488 */

    return 1;
}

QAC messages that encompass this guideline:

2771	Definite: These pointers address different objects.
2772	Apparent: These pointers address different objects.

Related rules:

Rule-18.3

The relational operators >, >=, < and <= shall not be applied to objects of pointer type except where they point into the same object

(c) The Motor Industry Research Association, 2012

QA C Source Code Analyser 8.1.2 MISRA C:2012 Compliance Module 1.0 © 2013 Programming Research www.programmingresearch.com

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