# V2562. MISRA. Expressions with pointer type should not be used in the '+', '-', '+=' and '-=' operations.

This diagnostic rule is based on the software development guidelines developed by MISRA (Motor Industry Software Reliability Association).

This diagnostic rule applies only to code written in C. Pointers should not be used in expressions with the operators '+', '-', '+=', and '-=' but can be used with the subscript '[]' and increment/decrement ('++'/'--') operators.

The use of address arithmetic makes the program less readable and may cause the maintainer to misinterpret the code. The use of indexing, on the contrary, is explicit and makes the code clearer; even if an expression using the subscript operator to index an array contains a mistake, it will be much easier to find. The same is true for increment/decrement operations: they explicitly convey the developer's intention to successively loop over a memory block that makes a continuous data region.

Example of non-compliant code:

    int arr[] = { 0, 1, 2 };
    int *p = arr + 1;        //+V2562
    p += 1;                  //+V2562

Fixed code:

    int arr[] = { 0, 1, 2 };
    int *p = &arr[1];
    ++p;
    int *q = p[1];

This diagnostic is classified as:

MISRA-C-2012-18.4 MISRA-C-2023-18.4 MISRA-CPP-2008-5.0.15