How to get the information about a lib/dll on Win and Mac

File Information :

On windows :

You can Dumpbin tool, which provide the whole information about any File.

MS Def: The Microsoft COFF Binary File Dumper (DUMPBIN.EXE) displays information about 32-bit Common Object File Format (COFF) binary files. You can use DUMPBIN to examine COFF object files, standard libraries of COFF objects, executable files, and dynamic-link libraries (DLLs).

On Mac : 

U can try lipo command:

lipo –info [file name]

 These tools are capable of  identifying the lib targets that they are meant for 32 bit or 64 bit systems.