Windows Store Apps, the Windows Runtime, and the C Run-Time

The latest version of this topic can be found at Windows Store Apps, the Windows Runtime, and the C Run-Time.

INCLUDEwin8_appname_long] apps are programs that run in the Windows Runtime that executes on Windows 8. The Windows Runtime is a trustworthy environment that controls the functions, variables, and resources that are available to a Windows 8.x Store app. However, by design, Windows Runtime restrictions prevent the use of most C Run-Time Library (CRT) features in Windows 8.x Store apps.

The Windows Runtime does not support the following CRT features:

• Most CRT functions that are related to unsupported functionality.

  For example, a Windows 8.x Store app cannot create a process by using the exec and spawn families of routines.

  When a CRT function is not supported in a Windows 8.x Store app, that fact is noted in its reference article.

• Most multibyte character and string functions.

  However, both Unicode and ANSI text are supported.

• Console apps and command-line arguments.

  However, traditional desktop apps still support the console and command-line arguments.

• Environment variables.

• The concept of a current working directory.

• Windows 8.x Store apps and DLLs that are statically linked to the CRT and built by using the /MT or /MTd compiler options.

  That is, an app that uses a multithread, static version of the CRT.

• An app that's built by using the /MDd compiler option.

  That is, a debug, multithread, and DLL-specific version of the CRT. Such an app is not supported on the Windows Store.

For a complete list of CRT functions that are not available in a Windows 8.x Store app and suggestions for alternative functions, see CRT functions not supported with /ZW.

See Also

Compatibility
Windows Runtime Unsupported CRT Functions
Run-Time Routines by Category