[previous] MISRA-C:2004  Rule  17.3:  (Required) [next] >, >=, <, <= shall not be applied to pointer types except where they point to the same array.
Attempting to make comparisons between pointers will produce undefined behaviour if the two pointers do not point to the same object. Note: it is permissible to address the next element beyond the end of an array, but accessing this element is not allowed.

Example Code: 



#include "misra.h"
#include "m2cmex.h"

extern S16 test_1703( void )
{
   S16 n = 0;
   static S8 tab1[] = "test1";
   static S8 tab2[] = "test2";
   S8 * ptr1;
   S8 * ptr2;

   ptr1 = &tab1[ u16a ];
   ptr2 = &tab1[ u16b ];

   if ( ptr1 > ptr2 )                /* OK */
   {
      n = 1;
   }

   ptr2 = &tab2[ u16c ];

   if ( ptr1 > ptr2 )               /* MISRA Violation */
   {
      n = 1;
   }

   return n;
}

QAC messages that encompass this guideline:

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

Related rules:

Rule  17.2 Pointer subtraction shall only be applied to pointers that address elements of the same array.


(c) The Motor Industry Research Association, 2004
QA C Source Code Analyser 8.1.2
MISRA-C:2004 Compliance Module 3.2
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