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Support for C11 and C17 standards requires Visual Studio 2019 version 16.8 or later. To see the documentation for this version, set the Visual Studio Version selector control for this article to Visual Studio 2019. It's found at the top of the table of contents on this page.

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Support for C11 and C17 standards is available starting in Visual Studio 2019 version 16.8. Support requires an updated Universal C Runtime (UCRT) and the latest Windows SDK updates, to work properly with the conforming preprocessor (/Zc:preprocessor).

Windows SDK releases correspond with Windows OS releases. Since there hasn't been a Windows release with these changes, you'll need an Insider Preview Windows SDK. That's a preview version of the Windows SDK that corresponds with Windows builds currently being flighted, or tested, by Windows Insiders. After you install the Insider Preview Windows 10 SDK, Visual Studio projects configured to use the latest Windows SDK will use the Insider Preview.

• Visual Studio 2019 version 16.8 or later installed and running on your computer. In the install, include the Desktop development with C++ workload. You can download the latest Preview from the Visual Studio Preview page. If Visual Studio isn't installed yet, see Install C++ support in Visual Studio for installation instructions.

Anyone can create a free Microsoft account and then opt into the Insider program. Go to the Windows Insider Program for Developers page, choose Register, and sign in.

After you register, you're given an option to start flighting Insider versions of Windows. This step isn't necessary to download and use the Insider Windows 10 SDK. When you register for Windows Insider, it doesn't automatically opt in your machines to download new Windows flights.

Once you get to the Welcome to the Windows Insider Program page, you don't need to choose Flight now. Continue to the next step to download the Insider Preview Windows 10 SDK.

You can install the Insider Preview Windows SDK from the Windows Insider Preview Downloads page. If you see a message that says "you need to be a member of the Windows Insider program," make sure you've signed in. Use the same Microsoft account you used for the Insider program. If you see a message that says "We are sorry, the page you requested cannot be found," try changing the locale in the URL to en-us.

The Insider page claims that use of a Windows 10 Insider Preview OS is required. It's only true for some of the content included in the Windows SDK. That content may depend on new APIs not present on older versions of Windows. However, the Windows and Universal C Runtime headers can install and are usable without an Insider OS.

Choose Get SDK Insider Preview – Build 20211 (or later) to begin the download. Later versions of the Windows SDK will also work.

The Insider Preview Windows SDK downloads as an .iso file. Open the folder that contains the downloaded file in File Explorer. Mount the .iso file, and then run WinSDKSetup.exe to start installation.

On the Specify Location page, select Install the Windows Software Development Kit - <version> to this computer, and then choose Next. On the Windows Kits Privacy page, select whether to allow Microsoft to collect insights for the Windows 10 Kits, then choose Next. Choose Accept to accept the license agreement. On the Select the features you want to install page, select only these features:

• Windows SDK Signing Tools for Desktop Apps

• Windows SDK for UWP Managed Apps

• Windows SDK for UWP C++ Apps

• Windows SDK for Desktop C++ x86 Apps (if you plan to build for x86)

• Windows SDK for Desktop C++ amd64 Apps (if you plan to build for amd64)

• Windows SDK for Desktop C++ arm Apps (if you plan to build for arm)

• Windows SDK for Desktop C++ arm64 Apps (if you plan to build for arm64)

Choose Install to install the selected SDK components. The SDK takes a couple of minutes to complete installation. When it completes, open Visual Studio.

In Visual Studio, open a new or existing C project, then open your project's Property Pages dialog.

Set the project to use the Insiders Preview Windows 10 SDK. On the Configuration Properties > General page, set the Windows SDK Version property either to 10.0 (latest installed version), or to the specific preview version you installed.

You'll also see a new option: C Language Standard. Set this property to ISO C11 Standard (/std:c11) or ISO C17 (2018) Standard (/std:c17).

The C++ Language Standard is used when the language is C++. It's the default when the file extension is .cpp. The C Language Standard version is used when the language is C. It's the default when the file extension is .c. To build using C11 or C17, put your source code in a .c file, or set the code to compile as C. You can set this property for your project on the Configuration Properties > C/C++ > Advanced page. Set the Compile As property to Compile as C code (/TC).

Congratulations, you've set up everything you need to build C11 and C17 code in Visual Studio!

/std (Specify language standard version)

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