# Lesson 22\. Pattern 14\. Overloaded functions

When porting a 32\-bit program to a 64\-bit platform, you may encounter changes in its logic related to the use of overloaded functions\. If a function is overlapped for 32\-bit and 64\-bit values, the access to it with an argument of a [memsize](https://pvs-studio.com/en/blog/terms/0030/)\-type will be translated into different calls on different systems\. This technique may be useful as, for example, in this code:

```cpp
static size_t GetBitCount(const unsigned __int32 &) {
  return 32;
}
static size_t GetBitCount(const unsigned __int64 &) {
  return 64;
}
size_t a;
size_t bitCount = GetBitCount(a);
```

But this change of logic is potentially dangerous\. Imagine a program that uses a class to arrange the stack\. This class is specific in that way that it allows you to store values of different types:

```cpp
class MyStack {
...
public:
  void Push(__int32 &);
  void Push(__int64 &);
  void Pop(__int32 &);
  void Pop(__int64 &);
} stack;
ptrdiff_t value_1;
stack.Push(value_1);
...
int value_2;
stack.Pop(value_2);
```

A careless programmer saves into and then selects from the stack values of different types \("[ptrdiff\_t](https://pvs-studio.com/en/blog/terms/0041/)" and "int"\)\. Their sizes coincide on the 32\-bit system and everything is quite okay\. But when the size of the type "ptrdiff\_t" changes on the 64\-bit system, the number of bytes saved into the stack gets larger than the number of bytes loaded then from the stack\.

I think this type of errors is clear to you and you understand that one should be very careful about calls to overloaded functions when passing actual arguments of a memsize\-type\.

## Diagnosis

[PVS\-Studio](https://pvs-studio.com/en/pvs-studio/) does not diagnose this pattern of 64\-bit errors\. First, it is explained by the fact that we have not encountered such an error in a real application yet, and second, diagnosis of such constructs involves some difficulties\. Please write to us if you encounter such an error in real code\.

_The course authors: Andrey Karpov \([karpov@viva64\.com](mailto:karpov@viva64.com)\), Evgeniy Ryzhkov \([evg@viva64\.com](mailto:evg@viva64.com)\)\._

_The rightholder of the course "Lessons on development of 64\-bit C/C\+\+ applications" is OOO "Program Verification Systems"\. The company develops software in the sphere of source program code analysis\. [The company's site](https://pvs-studio.com/en/)\._