Extracting Codes From Executable files...

There is one export table in each Win32 exe/dll file that has some functions to export.
If your file (with exe or dll extension or others) has some functions that listed in its export table, then it is a library (Dll) file. Otherwise it is not a library (Dll) and is executable.
Real executable files (without export table) dont have any functions that you can use.
If you want to extract & use some functions from exe file, it should be an interanlly library file (in spite of its extension).