Every Visual C++ project is linked with a C run-time library. This is called the CRT in Microsoft literature.
Depending on the support for multi-threading there are 2 kinds of CRT:
- Single threaded CRT: This can only be statically linked. This CRT is used if one of the compiler options
/MLor/MLdis specified. It would be linked withlibc.liborlibcd.librespectively for Release and Debug modes. The single-threaded CRT is completely deprecated and should not be used!![:x]()
- Multi-threaded CRT: This is the default kind of CRT and should be used always.
The type of linking (static or dynamic) and the configuration (Release or Debug), lead to 4 kinds of multi-threaded CRT:
- Release mode and statically linked: Specified using the compiler option
/MT. The library file used islibcmt.lib. - Debug mode and statically linked: Specified using the compiler option
/MTd. The library file used islibcmtd.lib. - Release mode and dynamically linked: Specified using the compiler option
/MD. The library file used ismsvcrt.liband the DLL file used at run-time ismsvcr100.dll(depends on Visual C++ version). - Debug mode and dynamically linked: Specified using the compiler option
/MDd. The library file used ismsvcrtd.liband the DLL file used at run-time ismsvcr100d.dll(depends on Visual C++ version).
Reference: C Run-Time Libraries at MSDN.
