[previous] 0487 [next] [C] If two pointers are subtracted, they must be pointers that address compatible types.
Constraint violations REFERENCE - ISO:C90-6.3.6 Additive Operators - Constraints

This is a constraint error

You are trying to subtract 2 pointers which point to objects of differing type. If the left hand operand of a subtraction operator is a pointer, the other operand must either be a pointer to a compatible object type or else an expression of integral type.

For example: 


/*PRQA S 510,3199,3203,3408,3447 ++*/

extern int   *pi;
extern short *ps;

void foo(void)
{
    long lx;

    lx = pi - ps;               /* Message 0487 */
}

MISRA-C:2004 Rules applicable to message 0487:

Rule  1.1  (Required) All code shall conform to ISO/IEC 9899:1990 C programming language, ISO 9899, amended and corrected by ISO/IEC 9899/COR1:1995, ISO/IEC 9899/AMD1:1995, and ISO/IEC 9899/COR2: 1996192

QA·C Source Code Analyser 8.1
MISRA-C:2004 Compliance Module 3.2
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