---
description: "Learn more about: Warning C26457 USE_STD_IGNORE_INSTEAD_OF_VOID_CAST"
title: Warning C26457
ms.date: 3/1/2021
f1_keywords: ["C26457", "USE_STD_IGNORE_INSTEAD_OF_VOID_CAST"]
helpviewer_keywords: ["C26457"]
---
# Warning C26457

> `(void)` should not be used to ignore return values, use '`std::ignore =`' instead (es.48)

## Remarks

Excerpt from the [C++ Core Guideline ES.48](https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es48-avoid-casts):

> Never cast to `(void)` to ignore a `[[nodiscard]]` return value. If you deliberately want to discard such a result, first think hard about whether that is really a good idea (there is usually a good reason the author of the function or of the return type used `[[nodiscard]]` in the first place). If you still think it's appropriate and your code reviewer agrees, use `std::ignore =` to turn off the warning which is simple, portable, and easy to grep.

Code analysis name: `USE_STD_IGNORE_INSTEAD_OF_VOID_CAST`

## Example

Use `std::ignore` instead of cast to `void`:

```cpp
struct S{};
[[nodiscard]] S getS();

void function() {
    (void) getS(); // C26457
    std::ignore = getS(); // OK
}
```