QA·C Help - 2820

	2820	Constant: Arithmetic operation on NULL pointer.

NULL pointers

Pointer arithmetic is being performed on a null pointer constant.

Internal representation of a null pointer constant is implementation-defined and may not necessarily be bitwise 0. A null pointer constant may be assigned or compared, but any attempt to perform arithmetic operations on it should be viewed as suspicious and non-portable.

For example:


/*PRQA S 489,507,2017,2983,2986,3199,3203,3408,4600 ++*/

#define NULL (void *)0

extern void foo(void)
{
    int *p;

    p = (int *)(NULL) + 1 ;            /* 2820 */
}

MISRA C:2012 Rules applicable to message 2820:

Rule-1.3 (Required)

There shall be no occurrence of undefined or critical unspecified behaviour

See also:

2810 Constant: Dereference of NULL pointer.
2811 Definite: Dereference of NULL pointer.
2812 Apparent: Dereference of NULL pointer.
2813 Suspicious: Dereference of NULL pointer.
2814 Possible: Dereference of NULL pointer.
2821 Definite: Arithmetic operation on NULL pointer.
2822 Apparent: Arithmetic operation on NULL pointer.
2823 Suspicious: Arithmetic operation on NULL pointer.
2824 Possible: Arithmetic operation on NULL pointer.

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MISRA C:2012 Compliance Module 1.0
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