FILE *通过函数的数组：FILE *或FILE **？

I'm trying to make a program which can work with several different files at the same time. My idea is to make an array of 20 FILE* in order to, if ever I arrive to this limit, to be able of closing one of them and open the new file requested. For this purpose I've thought in a function that selects an option and calls another that makes the job of saving (writing), closing and opening. After half week of searching through the web and making some proves, I've made two versions that seem to work: one with FILE* and another with FILE**.I'm trying to make a program which can work wit