The /Tc option specifies that filename is a C source file, even if it does not have a .c extension. The /Tp option specifies that filename is a C++ source file, even if it doesn't have a .cpp or .cxx extension. A space between the option and filename is optional. Each option specifies one file; to specify additional files, repeat the option.

/TC and /TP are global variants of /Tc and /Tp. They specify to the compiler to treat all files named on the command line as C source files (/TC) or C++ source files (/TP), without regard to location on the command line in relation to the option. These global options can be overridden on a single file by means of /Tc or /Tp.