unsigned int ref_count_{1};

};

}

#include <tuple>

[Using SAL Annotations to reduce code defects](using-sal-annotations-to-reduce-c-cpp-code-defects.md)

Because a lambda expression is typed, you can assign it to an **`auto`** variable or to a [`function`](../standard-library/function-class.md) object, as shown here:

}

The Microsoft C++ compiler binds a lambda expression to its captured variables when the expression is declared instead of when the expression is called. The following example shows a lambda expression that captures the local variable `i` by value and the local variable `j` by reference. Because the lambda expression captures `i` by value, the reassignment of `i` later in the program does not affect the result of the expression. However, because the lambda expression captures `j` by reference, the reassignment of `j` does affect the result of the expression.

}

This example declares a lambda expression that returns the sum of two integers and calls the expression immediately with the arguments `5` and `4`:

}

This example passes a lambda expression as an argument to the `find_if` function. The lambda expression returns **`true`** if its parameter is an even number.

}

You can nest a lambda expression inside another one, as shown in this example. The inner lambda expression multiplies its argument by 2 and returns the result. The outer lambda expression calls the inner lambda expression with its argument and adds 3 to the result.

}

Many programming languages support the concept of a *higher-order function.* A higher-order function is a lambda expression that takes another lambda expression as its argument or returns a lambda expression. You can use the [`function`](../standard-library/function-class.md) class to enable a C++ lambda expression to behave like a higher-order function. The following example shows a lambda expression that returns a `function` object and a lambda expression that takes a `function` object as its argument.

}

}

Because lambda expressions are typed, you can use them with C++ templates. The following example shows the `negate_all` and `print_all` functions. The `negate_all` function applies the unary **`operator-`** to each element in the `vector` object. The `print_all` function prints each element in the `vector` object to the console.

}

The body of a lambda expression follows the rules for both structured exception handling (SEH) and C++ exception handling. You can handle a raised exception in the body of a lambda expression or defer exception handling to the enclosing scope. The following example uses the **`for_each`** function and a lambda expression to fill a `vector` object with the values of another one. It uses a **`try`**/**`catch`** block to handle invalid access to the first vector.

}

The capture clause of a lambda expression cannot contain a variable that has a managed type. However, you can pass an argument that has a managed type to the parameter list of a lambda expression. The following example contains a lambda expression that captures the local unmanaged variable `ch` by value and takes a <xref:System.String?displayProperty=fullName> object as its parameter.

}

::: moniker range="msvc-160"

In Visual Studio 2019, the default target framework for .NET Core projects is 5.0. For .NET Frameworks projects, the default is 4.7.2. The .NET Framework version selector is on the **Configure your new project** page of the **Create a new project** dialog.

C++/CLI itself isn't installed by default when you install a Visual Studio C++ workload. To install the component after Visual Studio is installed, open the Visual Studio Installer. Choose the **Modify** button next to your installed version of Visual Studio. Select the **Installed components** tab. Scroll down to the **Compilers, build tools, and runtimes** section, and select the latest **C++/CLI support for v142 build tools** component. Choose **Modify** to update Visual Studio.