---
description: "Learn more about CppCoreCheck rule C26409: avoid explicit new and delete."
title: Warning C26409
ms.date: 12/14/2020
f1_keywords: ["C26409", "NO_NEW_DELETE"]
helpviewer_keywords: ["C26409"]
ms.assetid: a3b3a229-d566-4be3-bd28-2876ccc8dc37
---
# Warning C26409

> Avoid calling `new` and `delete` explicitly, use `std::make_unique<T>` instead (r.11).

Even if code is clean of calls to `malloc` and `free`, we still suggest that you consider better options than explicit use of operators [`new` and `delete`](../cpp/new-and-delete-operators.md).

**C++ Core Guidelines**:\
[R.11: Avoid calling new and delete explicitly](https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#r11-avoid-calling-new-and-delete-explicitly)

The ultimate fix is to use smart pointers and appropriate factory functions, such as [`std::make_unique`](../standard-library/memory-functions.md#make_unique).

## Remarks

- The checker warns on calls to any kind of operator **`new`** or **`delete`**: scalar, vector, overloaded versions (global and class-specific), and placement versions. The placement **`new`** case may require some clarifications in the Core Guidelines for suggested fixes, and may be omitted in the future.

Code analysis name: `NO_NEW_DELETE`

## Examples

This example shows C26409 is raised for explicit **`new`** and **`delete`**. Consider using smart pointer factory functions such as `std::make_unique` instead.

```cpp
void f(int i)
{
    int* arr = new int[i]{}; // C26409, warning is issued for all new calls
    delete[] arr;            // C26409, warning is issued for all delete calls

    auto unique = std::make_unique<int[]>(i); // prefer using smart pointers over new and delete
}
```

There's a C++ idiom that triggers this warning: `delete this`. The warning is intentional, because the C++ Core Guidelines discourage this pattern. You can suppress the warning by using the `gsl::suppress` attribute, as shown in this example:

```cpp
class MyReferenceCountingObject final
{
public:
    void AddRef();
    void Release() noexcept
    {
        ref_count_--;
        if (ref_count_ == 0)
        {
            [[gsl::suppress(i.11)]]
            delete this; 
        }
    }
private:
    unsigned int ref_count_{1};
};
```