Specifying Consistent Library Types

There are a number of Visual C++ run-time libraries that offer the same entry points but have different characteristics. The default Visual C++ library is libc.lib, which is single threaded, non-debug, and static. The Visual C++ and Visual Fortran libraries must be the same types. The incompatible types are:

Mixing single-threaded with multi-threaded versions of the libraries
Mixing static and dynamic-link versions of the libraries
Mixing debug with non-debug versions of the libraries

The default Fortran libraries depend on the project type:

Fortran Project Type	Default Libraries Used
Fortran Console	Static, single-threaded libraries dfor.lib and libc.lib
Fortran Standard Graphics	Static, multithreaded libraries dformt.lib and libcmt.lib
Fortran QuickWin	Static, multithreaded libraries dformt.lib and libcmt.lib
Fortran Windows	Static, multithreaded libraries dformt.lib and libcmt.lib
Fortran DLL	Dynamic-link libraries dfordll and msvcrt (and their import libraries)
Fortran Static Library	Static, single-threaded libraries dfor.lib and libc.lib

Pure Fortran applications can have mismatched types of libraries. One common scenario is a Fortran QuickWin application that links with a Fortran Static library. Fortran QuickWin (and Fortran Standard Graphics) applications must use the static, multithreaded libraries, and by default, Fortran Static libraries are built using static, single-threaded libraries. This causes a conflict, so the Fortran Static library and the QuickWin application must both be built using static, multithreaded libraries.

Similarly, different C/C++ applications link against different C libraries. If you mix the different types of applications without modifying the defaults, you can get conflicts. The debug version of a library has a letter "d" appended to its base file name:

Static, single-threaded: libc.lib and libcd.lib
Static, multithreaded: libcmt.lib and libcmtd.lib
Dynamic-link libraries: msvcrt and msvcrtd (.lib import library and .dll)

When using a Debug configuration, Visual C++ selects the debug libraries. Visual Fortran does not select debug libraries for any configuration, but provides a Project Settings option to request their use. To specify different types of Fortran libraries in the visual development environment, open the Project Settings dialog box, click the Fortran tab, and select the Libraries category:

To specify static libraries, select the appropriate type of static (non-DLL) library under Use Run-Time Libraries (see /libs:static)
To specify dynamic-link libraries, select the appropriate type of DLL library under Use Run-Time Libraries (see /libs:dll)
To specify multithreaded libraries, select the appropriate type of Multi-thread library under Use Fortran Run-Time Libraries (see /threads).
To specify the debug libraries, select the appropriate type of Debug library under Use Run-Time Libraries (see /[no]dbglibs). If you specify debug libraries (/dbglibs) and also request DLL libraries (/libs:dll) (Use Run-Time Libraries that include both Debug and DLL), be aware that this combination selects the debug versions of the Fortran DLLs. These Fortran DLL files have been linked against the C debug DLLs.
When you specify QuickWin or Standard Graphics libraries under Use Run-Time Libraries, this selection implicitly requests Multi-threaded libraries.

For details about the Visual C++ libraries used and compiler options available, see Visual Fortran/Visual C++ Mixed-Language Programs.