Compiling with /c creates .obj files only. You must call LINK explicitly with the proper files and options to perform the linking phase of the build.

Any internal project created in the development environment uses the /c option by default.

To set this compiler option in the Visual Studio development environment

To set this compiler option programmatically

The following command line creates the object files FIRST.obj and SECOND.obj. THIRD.obj is ignored.

CL /c FIRST.C SECOND.C THIRD.OBJ

To create an executable file, you must invoke LINK:

LINK firsti.obj second.obj third.obj /OUT:filename.exe

Reference