c++ - Struct type "does not provide a subscript operator" -

i trying read values file array of structs. however, keep getting compiler errors tell me struct, books, not provide subscript operator , lost.

the struct contained in header file while declaration of array of structs in main(). here (relevant) code functions.h header file:

#ifndef functions_h #define functions_h #include <iostream> #include <string> #include <fstream> using namespace std;  struct books {         int isbn;         string author;         string publisher;         int quantity;         double price; };   class functions {         public:                 void read_inventory(books, int, int);  };   // function definitions  void read_inventory(books array, int max, int position) {         ifstream inputfile;         inputfile.open("inventory.dat");          inputfile >> array[position].isbn;         inputfile >> array[position].author;         inputfile >> array[position].publisher;         inputfile >> array[position].quantity;         inputfile >> array[position].price;          cout << "the following data read inventory.dat:\n\n"              << "isbn: " << array[position].isbn << endl              << "author: " << array[position].author << endl              << "publisher: " << array[position].publisher << endl              << "quantity: " << array[position].quantity << endl              << "price: " << array[position].price << endl << endl; } 

and here array of struct declaration in main along how used:

#include <iostream> #include <string> #include <fstream> #include "functions.h" using namespace std;  int main() {         const int max_size = 100;         int size, choice;         functions bookstore;         books booklist[max_size];          cout << "select choice\n\n";              cin >> choice;              size = choice;              switch (choice)             {                     case 1: bookstore.read_inventory(booklist[choice], max_size, size);                             break;               } } 

once compiled, 10 error messages (one each time use array[position]) state: error: type 'books' not provide subscript operator

there many problems in code, define read_inventory global function. might have received there undefined reference functions::read_inventory. problem pass books instead of books* can't use [] operator.

change

void read_inventory(books array, int max, int position)  { 

to

void functions::read_inventory(books* array, int max, int position) { 

now have changed parameter type, change line

case 1: bookstore.read_inventory(booklist[choice], max_size, size); 

to

case 1: bookstore.read_inventory(booklist, max_size, size);