# V3537\. AUTOSAR\. Subtraction, \>, \>\=, <, <\= should be applied only to pointers that address elements of the same array\.

This diagnostic rule is based on the software development guidelines developed by [AUTOSAR](https://www.autosar.org/) \(AUTomotive Open System ARchitecture\)\.

The C/C\+\+ standard specifies \(C\+\+17 § 8\.5\.9 paragraph 3\) that applying the operator '\-', '\>', '\>\=', '<', or '<\=' to two pointers that do not point to the elements of the same array is undefined/unspecified behavior\. Therefore, if two pointers point to different array objects, then these objects must be elements of the same array to be comparable\. 

Example of non\-compliant code:

```cpp
int arr1[10];
int arr2[10];
int *pArr1 = arr1;
if (pArr1 < arr2)
{
  ....
}
```

The following code is also non\-compliant:

```cpp
int arr1[10];
int arr2[10];
int *pArr1 = &arr1[1];
int *pArr2 = &arr2[1];
int len = pArr1 - pArr2;
```

To learn more about why pointer comparisons may lead to errors, see the article: "[Pointers are more abstract than you might expect in C](https://pvs-studio.com/en/blog/posts/cpp/0576/)"\.