My goal is to be able to call a specific function many times successively with a new/undeclared array as a parameter being passed
Your goal is to write a C/C++ program using a syntax that isn't supported by the language? Why? What has this got to do with writing a program to solve a particular problem?
I'm hoping I don't have to declare it beforehand (doubling the number of lines of code)
Again, why is this a problem? If it requires a few more lines of code to get the job done, then that is what you have to do.
Pete