C ++实例变量/指向堆中数组的指针

Question

I have an dynamic array of structures. When I say dynamic, I mean that the number of elements can vary from each time the program is ran. After having difficulty trying to use the instance variable as an array, I've been having incompatible types problems. Is there any other methods?

I have this structure:

struct movie
  {
    int rank;
    string title;
    string distributor;
    string weekend;
    string total;  
} ;

I have this class header file :

class ReadFile{

public:
    ifstream moviesFile;
    movie movies[];  

    ReadFile(string);
    movie handleLine(string);
    string getString(vector<char>);

};

This is how I'm trying to instantiate the movies instance variable:

//Some code
movie temparray[linecount];
//temparray is filled with various movie structures.
movies = temparray;

This is when I get my error. How would I accomplish my task of instantiating my movies array. Thankyou!

Answer 1

Arrays are non-modifiable lvalues so you cannot assign to them

So movies = temparray; is illegal

In C++ it is always recommended that you use a std::vector instead to C-style arrays

//....
public:
    ifstream moviesFile;
    std::vector<movie> movies;  

//....

//Some code
 movie temparray[linecount];
 movies.assign(temparray, temparray+linecount);

Answer 2

You can not define arrays of unknown size in C++, use std::vector<movie> movies; to create a dynamic array.