C语言。 如何管理函数返回的结构体？

Question

I am a beginner in C and programming overall, so sorry for the possible trivial mistakes. Let me briefly explain my case.

I have the struct students:

typedef struct {
    int id;
    char name[20]
    int grade;
} students;

and I have the variable students student[20] that contains names, ids and grades of each student

and also have a pointer function of type students (I hope I am calling it properly, correct me if wrong) which has to return the pointer to the student with the highest grades:

students* topStudent(students student[20]) {
    ...
    //let's say I have found the student with the top grades and his index is 4.

    return &student[4];
}

Now, let's say I want to manage this student[4], but, How do I do that? For instance, I want to have student[4] 's fields (id, etc.) copied in another variable students topstudent so that I directly worked with it further.

I tried this:

students *topstudent;
topstudent = topStudent(student);

but whenever I try to work with topstudent , for example like this:

printf("%i %s %i", topstudent.id, topstudent.name, topstudent.grade);

or when I tried to put & before the topstudent.id , topstudent.name and topstudent.grade , it gives 3 errors for each of the fields ( request for member 'name' in something not a structure or union ). (I guess there's something wrong with the declaration and using of topstudent , or I am not applying correct methods for pointers, or something else I am missing).

So, could you please tell me the correct way of doing that? Feel free to get to know the details, if needed. Thank you, I do appreciate your help!

Answer 1

topstudent is a pointer, so you have to dereference that to access the structure.

You can use unary * operator to dereference a pointer.

printf("%i %s %i", (*topstudent).id, (*topstudent).name, (*topstudent).grade);

Alternatively, you can use -> operator. A->B means (*A).B .

printf("%i %s %i", topstudent->id, topstudent->name, topstudent->grade);