How to create .obj and .h file of a C code file in windows [closed]

  .obj, c++, header-files, windows

I have a function add() in a c code file "add.c". I want to use these functions in another c program let’s call it "a.c". How can I do it by creating a header file "add.h".
I am a beginner and I tried searching on google about it but I could only find how to do it on Linux/Unix but not on the windows (cmd). Can someone explain how to do it on windows.

Source: Windows Questions