---
title: C26486
ms.date: 12/14/2018
ms.topic: "conceptual"
f1_keywords: ["C26486"]
helpviewer_keywords: ["C26486"]
ms.assetid: d5395efc-5eb2-4e82-9b45-fcd5ff4577bf
author: kylereedmsft
ms.author: kylereed
---
# C26486 LIFETIMES_FUNCTION_PRECONDITION_VIOLATION

Don't pass a pointer that may be invalid (dangling) as a parameter to a function.

```cpp
void use(int*);

void ex1()
{
    int* px;
    {
        int x;
        px = &x;
    }

    use(px);  // px is a dangling pointer
}
```

## Remarks

The Lifetime guidelines from the C++ core guidelines outline a contract that code can follow which will enable more thorough static memory leak and dangling pointer detection. The basic ideas behind the guidelines are:

- Never dereference an invalid (dangling) or known-null pointer
- Never return (either formal return or out parameter) any pointer from a function.
- Never pass an invalid (dangling) pointer to any function.

## See also

- [C++ Core Guidelines Lifetimes Paper](https://github.com/isocpp/CppCoreGuidelines/blob/master/docs/Lifetime.pdf)