C++ User's Guide

Definitions Search Path

As an alternative to the normal search path set with -I, you can specify a search directory for template definition files with the option -ptidirectory. Multiple -pti flags define multiple search directories--that is, a search path. If you use -ptidirectory, the compiler looks for template definition files on this path and ignores the -I flag. Since the -ptidirectory flag complicates the search rules for source files, use the -I option instead of the -ptidirectory option.