What is the function pointer parameters

Question

thats mean what is the usage and how to use

Answer 1

I'm not quite sure I understand the question, but I'll guess you're asking why would you use pointers instead of variables as function parameters.
Well, at least in C, if you put a variable as parameter, it just copies the value, and a function can only return one value. Now imagine I have a character and I want to move its x and y possition in one function. The only way of doing that is passing those values as pointers. When the function changes those values, they Will not be a copy but the actual values because the pointers refference their memory adress.
Was that your question or I missunderstood? If that's the case, could you be more specific?