Xbox One C Runtime Library
The C Runtime Library (CRT) is a set of dlls that provide access to common programming tasks such as string manipulations, the Windows Runtime Extensions and STL. This overview describes various aspects of the Xbox One CRT, including the available features, build options and the available APIs.
Surface Area
The surface area for the Xbox One CRT is aligned with the CRT provided for Microsoft Store apps. You’ll find this surface area to be smaller than that provided for Windows desktop applications or Xbox 360 titles.
The following list summarizes the differences between the CRT for Microsoft Store apps and the CRT for Xbox One apps.
- Much of the legacy Microsoft-specific extensions to the CRT (_beep, _seterrormode, _setsystime, _loaddll, etc) are not present. Most of these were deprecated with VS 2005 when the CRT moved to more standard POSIX & ANSI function names. Many of the functions have equivalent APIs in the platform.
- Multi-byte string functions have been removed because Xbox One is a Unicode platform.
- Current working directory (chdir, getcwd, etc) is fixed to the app package root.
- Console I/O (cwprintf, etc) functions have been removed as there is no supported user-visible console.
- Port I/O (inp, outp, etc) have been removed since apps do not have access to this functionality.
- Pipe I/O has been removed.
- Relative paths passed to file I/O functions will be resolved relative to the package root.
- Some extended device functionality (_getdrive, _getdrives, etc) has been removed. Generally, this functionality is not available to Microsoft Store apps and doesn’t apply to Xbox One games as the hardware is fixed.
- Process control functions (spawn, exec, etc) have been removed. While Xbox One games have access to this functionality, Microsoft Store apps do not.
- No access to environment variables (getenv et al). While Xbox One games have access to this functionality, Microsoft Store apps do not.
- Microsoft extensions for threading have been removed (_beginthreadex, etc). These functions are obsolete and CreateThread should be used instead. The Xbox One CRT also supports C++ 2011 std::thread features.
- Some heap debugging features have been removed.
See http://msdn.microsoft.com/en-us/library/hh674596.aspx for the list of CRT functions that are not supported for Microsoft Store apps or Xbox One.
Building and Linking
Xbox One games must use the DLL version of the CRT. Static linking is not supported. Use either /MD or /MDd when specifying how to include the CRT.
Note Explicitly adding msvcrt(d).dll and vccorlib(d).dll (in that order) to the link command line of a D3D project results in an error during link that states that the symbol __crtWinrtInitType is defined multiple times. To avoid this error switch the order of msvcrt(d).dll and vccorlib(d).dll on the link command line. This error does not occur in projects created with the default template.
Packaging the CRT
The Xbox One CRT is included in the operating system image that is packaged with your title. There is no need to take any special steps to include the CRT with your game.
Xbox One CRT Features
The following sections summarize the features provided by the Xbox One CRT.
C++/CX Support
The Windows Runtime Extensions (also referred to as C++/CX) is fully supported on Xbox One. Use the /ZW compiler switch to enable this feature for your projects.
ATL and MFC Support
ATL and MFC are not supported in the Xbox One CRT.
STL Support
STL is fully supported in the Xbox One CRT.
PPL Support
PPL is fully supported in the Xbox One CRT.
AMP and OpenMP Support
AMP and OpenMP are fully supported in the Xbox One CRT.