错误:classname没有命名类型

我是一个从指针开始的中级学生。我试图将数据存储在数组中，稍后由搜索函数调用。当我试图编译时，我被告知"error: retail does not name a type"，我不明白这是什么意思，也不知道如何修复它。

// ********************************************************
// Starting Out with C++                                  *
// From Control Stuctures through Objects                 *
// seventh edition                                        *
//                                                        *
// Chapter 8 Searching and Sorting Arrays                 *
//                                                        *
// Serendipity Booksellers Software Development           *
// Project — Part 8: A Problem-Solving Exercise           *
//                                                        *
// Multi-File Program                                     *
// ********************************************************
#include "bookinfo.h"
#include "cashier.h"
#include "invmenu.h"
#include "reports.h"
#include <iostream>
using namespace std;
// Constant for array sizes
const int SIZE = 20;
// Global Arrays
string bookTitle[SIZE];
string isbn[SIZE];
string author[SIZE];
string publisher[SIZE];
string dateAdded[SIZE];
int qtyOnHand[SIZE];
double wholesale[SIZE];
double retail[SIZE];
retail[SIZE] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
wholesale[SIZE] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
qtyOnHand[SIZE] = {10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10,10};

dateAdded[0] = "1/1";
dateAdded[1] = "1/1";
dateAdded[2] = "2/1";
dateAdded[3] = "3/1";
dateAdded[4] = "4/1";
dateAdded[5] = "5/1";
dateAdded[6] = "6/1";
dateAdded[7] = "7/1";
dateAdded[8] = "8/1";
dateAdded[9] = "9/1";
dateAdded[10] = "10/1";
dateAdded[11] = "11/1";
dateAdded[12] = "12/1";
dateAdded[13] = "13/1";
dateAdded[14] = "14/1";
dateAdded[15] = "15/1";
dateAdded[16] = "16/1";
dateAdded[17] = "17/1";
dateAdded[18] = "18/1";
dateAdded[19] = "19/1";

author[0] = "0";
author[1] = "1";
author[2] = "2";
author[3] = "3";
author[4] = "4";
author[5] = "5";
author[6] = "6";
author[7] = "7";
author[8] = "8";
author[9] = "9";
author[10] = "10";
author[11] = "11";
author[12] = "12";
author[13] = "13";
author[14] = "14";
author[15] = "15";
author[16] = "16";
author[17] = "17";
author[18] = "18";
author[19] = "19";
bookTitle[0] = "0";
bookTitle[1] = "1";
bookTitle[2] = "2";
bookTitle[3] = "3";
bookTitle[4] = "4";
bookTitle[5] = "5";
bookTitle[6] = "6";
bookTitle[7] = "7";
bookTitle[8] = "8";
bookTitle[9] = "9";
bookTitle[10] = "10";
bookTitle[11] = "11";
bookTitle[12] = "12";
bookTitle[13] = "13";
bookTitle[14] = "14";
bookTitle[15] = "15";
bookTitle[16] = "16";
bookTitle[17] = "17";
bookTitle[18] = "18";
bookTitle[19] = "19";
isbn[0] = "0";
isbn[1] = "1";
isbn[2] = "2";
isbn[3] = "3";
isbn[4] = "4";
isbn[5] = "5";
isbn[6] = "6";
isbn[7] = "7";
isbn[8] = "8";
isbn[9] = "9";
isbn[10] = "10";
isbn[11] = "11";
isbn[12] = "12";
isbn[13] = "13";
isbn[14] = "14";
isbn[15] = "15";
isbn[16] = "16";
isbn[17] = "17";
isbn[18] = "18";
isbn[19] = "19";

int main()
{
    int choice = 0; // To hold the user's menu choice
    // Display the menu until the user selects item 4
    while (choice != 4)
    {
        cout << "Serendipity Booksellersn";
        cout << "tMain Menunn";
        cout << "1.Cashier Modulen";
        cout << "2.Inventory Database Modulen";
        cout << "3.Report Modulen";
        cout << "4.Exitnn";
        // Get the menu choice as input from the user
        cout << "Enter Your Choice: ";
        cin >> choice;
        // Validate the user's input
        while (choice < 1 || choice > 4)
        {
            cout << "nPlease enter a number in the range 1 - 4.n";
            cout << "Enter Your Choice: ";
            cin >> choice;
        }
        // Display a selection message
        {
            switch (choice)
            {
                case 1:
                    cashier();
                    break;
                case 2:
                    invMenu();
                    break;
                case 3:
                    reports();
                    break;
                case 4:
                    cout << "nYou selected item 4.n";
                    break;
            }
        }
        cout << endl << endl;
    }
    return 0;
}

如何初始化数组失败?我的声明格式是否不正确?