You don't have to know. Library functions are also written by somebody, aren't they?
If you have written it yourself, then it is the former, otherwise it is the latter.
No, once you call a library (or any) function, you have to wait until it has returned.Of course the function may call itself, but you do not know or care of that.
It depends on what information you have: whether you know the wave function or you know the speed and wavelength.
Declared is the right word. (Don't define functions in headers, unless you really know what you are doing.)
I will define this word so that you will know what the word means.
it is important to use a library because you have to know the strategy of knowing how to do every in the library
Experience. Nobody can tell you what you are thinking to any useful degree, and love is something one must discover and define for themselves.
They define them through myths and folktales as to why i do not know either
This depends on your definition of God. Since we do not really know anything about God, even whether he exists, it is certainly easier to define attributes that we believe do not apply to him than to define attributes we feel certain do apply to him.
It doesn't matter what language the external program or function was written in since all executables must be converted to machine code. To execute an external function, that function must reside in a library to which your program is linked and you must know the prototype of the function you intend to call. This is usually found in the library header file which can simply be included in your program. You can then call the external function just as you would an internal function. To execute a specific function in another program, however, you must use the command line interface for that program.
i do not know
i want to know that too :(