为什么我会收到错误"Array type Item[1000] is not assignable"？

我对 c++ 很陌生，我需要一些关于这个错误的帮助，"数组类型 Item[1000] 不可分配" ？顺便说一下，我在XCode上，我知道我应该在Windows上。这是学校的家庭作业，所以如果你可以指导我，而不会放弃太多，那会很棒。哦，对不起如果我搞砸了什么，这是我的第一篇文章。

#include <iostream>
#include <string>
#include <fstream>
using namespace std;
//global constant
const int MAX_SIZE = 1000;
//make an Item class
class Item
{
private:
    string id;
    int sold, remain;
public:
    void set_id(string _id);
    void set_sold(int _sold);
    void set_remain(int _remain);
};
//all the methods setting id, sold, and remaining
void Item::set_id(string _id){
    id = _id;
}
void Item::set_sold(int _sold){
    sold = _sold;
}
void Item::set_remain(int _remain){
    remain = _remain;
}
//code to read from file
ifstream inFile;
ofstream outFile;
//function that reads file to array
void read_In()  **I think it's because this should not be a void**
{ 
    //variables
    int ct = MAX_SIZE;
    Item a[MAX_SIZE];
    //open the file
    inFile.open( "inventory.txt" );
    //while the file hasn't ended, read and place into array of Items
    while( !inFile.eof() ){
        string for_id = "";
        int for_sold = 0;
        int for_remain = 0;
        for(int i = 0;i<ct;i++){
            //store the next thing on the file to the array of Items
            inFile >> for_id;
            a[i].set_id(for_id);
            inFile >> for_sold;
            a[i].set_sold(for_sold);
            inFile >> for_remain;
            a[i].set_remain(for_remain);
        }
    }
    inFile.close();
}
int main(){
    Item sp[MAX_SIZE];
    sp = read_In();  **Apparently the error is here!**
    system("pause");
    return 0;
}