Custom Build Not happen every time.

we have fresh code in VC++ which has some custom build event( which has make file to generate some header files), and after building the project. if i remove the newly created header files as well as debug folder and try to again build the project, project does not perform custom build event, it directly start compiling, so we got some error.

but without deleting if i use clean project, it works perfectly. so what the clean process is doing...

any help is appreciated...

Clean deletes the temporary files like .OBJ from the debug folder.
You will probably need to do a rebuild after you delete the header files.