C++ can't access a public attribute in a class that is returned by the vector's iterator

Question

So I have this class called order, and when a user places an order i invoke that class. I have another class called orderbook, it is a vector of orders.

I wanted to try to traverse the orderbook upon receipt of a new order to check if there are duplicates, but right now i am stuck traversing the vector.

I am using the iterator and comparing the new order's symbol vs each order in my orderbook's symbol.

I read that the iterator is like a pointer and it will return the memory location of my vector's orders and *it would give me the order itself and if I add a .symbol to the it that should give me the order's symbol attribute, but right now it won't even compile.

I get this error when I try:

../src/oncemore.cpp:123:40: error: 'std::vector<order>::iterator' {aka 'class __gnu_cxx::__normal_iterator<order*, std::vector<order> >'} has no member named 'symbol'
  123 |    if (_clientOrder.symbol.compare(*it.symbol)==0) {}
      |                                        ^~~~~~

below is the code, I have deleted a bunch of stuff not relevant to the question.

 
#include <iostream>
#include <iterator>
#include <sstream>
#include <string>
#include <string.h> 
#include "windows.h"
#include <vector>
#include <chrono>
#include <algorithm>
using namespace std;

 

class order {



  public:

    string orderID; 
    char buysell;
    string symbol;
    double price;
    int qty;


    void newOrder(string &_orderID, char &_buysell, string &_symbol, double &_price, int &_qty){
        orderID=_orderID;
        buysell=_buysell;
        symbol=_symbol;
        price=_price;
        qty=_qty; 
    }
 


};

class orderbook {
  private:
    string orderID; 
    char buysell;
    string symbol;
    double price;
    int qty;
    vector<order> the_orderbook;
    vector<order>::iterator it;



  public:

    string insert(order &_clientOrder){ 
     
        for (it = the_orderbook.begin(); it != the_orderbook.end(); it++) {

 
            if (_clientOrder.symbol.compare(*it.symbol)==0) {} <-- this line fails

        }
 

        the_orderbook.push_back(_clientOrder);
        return "bla";

    }


};

int main() {


    cout << "!!!Hello once more" << endl; // prints !!!Hello once more

    string user_input = "";

    string done= "done trading";
    string orderID;
    string orderaction;
    string orderRecvedTime;
    char buysell;
    string symbol;
    double price;
    int qty;

    string error;
    orderbook thebook;
    order user_order; 

    while(user_input.compare(done) != 0) {
        cout << "enter order"<< endl;
        getline(cin, user_input);

        stringstream lineStream(user_input);
        lineStream >>orderaction>>orderID>> buysell >> symbol >> price>> qty;
 


        if (orderaction.compare("D") == 0) {
            string tag150;
            user_order.newOrder(orderID, buysell,symbol,price,qty);
            tag150 = thebook.insert(user_order);


            cout << "You made a new order."<< endl; 
    }

    return 0;
}

Answer 1

When you write

*it.symbol

since the operator precedence for . is higher than *, so the expression becomes:

*(it.symbol)

and the error says that an iterator doesn't have a member named symbol which is true.

---

You can force the precedence by doing:

(*it).symbol

or even better, by using the appropriate operator:

it->symbol