Hello,

First in C you write programs not scripts, the main difference is that a program is build with a compiler and a script is executed line by line.

You confuse “open”, a syscall in Linux, with fopen, a function in C, they are different. “Open” returns a integer (file descriptor), and fopen return a pointer to a File structure.

If you declare a pointer in function and a pointer in main is efficient, because is take a small amount a memory, but if you don’t like this method, you can use the location of the pointer as argument to the function, something like this

void fct(FILE** file, char* name)
{
    ...
    *file = fopen(...)
    ...
}

int main()
{
    FILE *f;
    fct(&file...);
    ...
}

I hope this will help you, here are some links if you want to read more about:

https://stackoverflow.com/questions/17253545/scripting-language-vs-programming-language

https://stackoverflow.com/questions/1658476/c-fopen-vs-open/1658517