---
title: C26452
description: "Describes causes of MSVC Code analysis warning C26452, and how to fix the issue."
ms.date: 07/15/2020
ms.topic: "reference"
f1_keywords: ["C26452"]
helpviewer_keywords: ["C26452"]
dev_langs: ["C++"]
---
# Warning C26452

> Arithmetic overflow: Left shift count is negative or greater than or equal to the operand size, which is undefined behavior

This warning indicates the shift count is negative, or greater than or equal to the number of bits in the shifted operand. Either case results in undefined behavior.
C4293 is a similar check in the Microsoft C++ compiler.

## Example

```cpp
unsigned __int64 combine(unsigned lo, unsigned hi)
{
  return (hi << 32) | lo; // C26252 here
}
```

To correct this warning, use the following code:

```cpp
unsigned __int64 combine(unsigned lo, unsigned hi)
{
  return (static_cast<unsigned __int64>(hi) << 32) | lo; // OK
}
```

## See also

[ES.102: Use signed types for arithmetic](https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#Res-unsigned)