The difference between traditional DLL and COM DLL

Question

I am currently studying COM. I found that COM DLL is kind of built upon the traditional DLL infrastructure. When we build COM DLLs, we still rely on the traditional DLL export m

Answer 1

In addition to the answers already posted, COM interfaces expose binary data objects in a programming language independent manner, that allows memory for these objects to be allocated in one process address space and freed in another. Lookup marshalling and unmarshalling.

It also allows strings to be passed without paying attention to details of encoding to determine where a null-terminator might be. COM strings are counted UNICODE strings.

Throw in IDL and compile the type library into the DLL, and you have self-describing interfaces. With plain DLLs, you have to know from the external docs what methods they have and the parameters they take.

The COM standard can be cross-platform, as well. Mac versions of Office support COM, and there have been implementations for Unix and Unix-like systems, although they have never been popular.