I was curious about .obj files: I pretty much don\'t know what they are (or what they contain), so I opened them with Vim text editor and what I found inside was an
.obj
The .obj files used by link.exe has MS COFF format.
link.exe
You can find "Microsoft PE and COFF Specification" here, and parse .obj file according to it.
Or, you can use existing tool like dumpbin.
dumpbin