c ++错误c2679：二进制'['：未找到采用'SalesItem'类型的右侧操作数的运算符（或者没有可接受的转换）

Question

I am new to this site (apologies if I am doing this wrong,) and fairly new to c++. I have run into an annoying error with an assignment for my c++ class

c++ error c2679: binary '[' : no operator found which takes a right-hand operand of type 'SalesItem' (or there is no acceptable conversion)

I'm not really sure what I need to include to help get an answer. I have included what I think to be the most relevant classes, leaving out the class with main(). I have not included the headers, but I should be able to add those in if needed...

Here is the Invoice class where I am finding this error, I have marked the lines where the error occurs with astriks(*):

#include "stdafx.h"
#include <iostream>
#include "Invoice.h"
#include <vector>
#include <string>
using namespace std;

static int nextInvoiceNum = 1000;
Invoice::Invoice(const string name, const int vectorSize)
{
    customerName = name;
    salesItems.reserve(vectorSize);
    invoiceNumber = nextInvoiceNum++;
}

void Invoice::setCustomerName(string name)
{
    customerName = name;
}
string Invoice::getCustomerName()
{
    return customerName;
}
int Invoice::getInvoiceNumber()
{
    return invoiceNumber;
}
void Invoice::display()
{
    cout << "-------------------------\n";
    cout << "\n Invoice #: " << getInvoiceNumber() << "\n";
    cout << "\n Customer name: " << getCustomerName() << "\n";
    cout << "-------------------------\n";
    cout << "Items Purchased";
    cout << "-------------------------\n";
    for (auto &item : salesItems)
    {
********cout << salesItems[item].display() << "\n";
        cout << "-------------------------\n";
    }
}

void Invoice::addSalesItem(SalesItem&)
{
    salesItems.push_back(SalesItem());
}

double Invoice::getInvoiceAmount()
{
    double runningTot = 0;
    double total = 0;
    for (auto &item : salesItems)
    {
********runningTot = salesItems[item].getPartQuantity() * salesItems[item].getPartPrice();
        total += runningTot;
    }
    return total;
}

Invoice::~Invoice(void)
{
}

What I am attempting to do is use a vector of objects and where the error first occurs is when I try to call the display() method from the SalesItems class using the vector.

Here is the SalesItem class:

#include "stdafx.h"
#include "SalesItem.h"
#include <iostream>
using namespace std;


SalesItem::SalesItem(string partNumber, string partDescription, int partQuantity, double partPrice)
{
    partNumber = "";
    partDescription = "";
    partQuantity = 0;
    partPrice = 0;
}


SalesItem::~SalesItem(void)
{
}

void SalesItem::setPartNumber(string number)
{
    partNumber = number;
}
void SalesItem::setPartDescription(string description)
{
    partDescription = description;
}
void SalesItem::setPartQuantity(int quantity)
{
    partQuantity = quantity;
}
void SalesItem::setPartPrice(double price)
{
    partPrice = price;
}

string SalesItem::getPartNumber()
{
    return partNumber;
}
string SalesItem::getPartDescription()
{
    return partDescription;
}
int SalesItem::getPartQuantity()
{
    return partQuantity;
}
double SalesItem::getPartPrice()
{
    return partPrice;
}

void SalesItem::display()
{
    cout<< "-------------------------:";
    cout<< "\n Part number: " << getPartNumber() << "\n";
    cout<< "\n Part description: " << getPartDescription() << "\n";
    cout<< "\n Part quantity: " << getPartQuantity() << "\n";
    cout<< "\n Part price: $" << getPartPrice() << "\n";
    cout<< "\n Invoice amount: $" << getInvoiceAmount() << "\n";
}

double SalesItem::operator+(double total)
{
    double subtotal = getPartQuantity() * getPartPrice();
    total += subtotal;
    return total;
}

double SalesItem::getInvoiceAmount()
{
    double invoice = getPartQuantity() * getPartPrice();
    return invoice;
}

Again, sorry if I'm posting this in the wrong way. I would really appreciate some help with this. Will provide any other necessary info or make changes on a timely basis.

Thanks!

Answer 1

It's saying that the thing inside the square brackets is a salesItem object, but it was expecting an integer. The normal use of square brackets is to pick out one item out of a collection, using some kind of index, usually an integer. In this case, though, your for loop has already picked the item out, so you can just say "item.display()" instead of "salesItem[item].display()".

(You'd use salesItem[item].display() if instead your code looked sort of like this:)

int item;
for (item=0; item < ?however many sales items you have? ; item++) {
    bla bla salesItem[item].display()
}

Answer 2

Your range for loop puts the reference to the item in item , not the index. Instead of salesItems[item] use item .