如何在C ++中声明高分辨率时钟的变量

Question

在此示例中：https://en.cppreference.com/w/cpp/chrono/high_resolution_clock/now

他们用auto一词声明了时钟时间点。

auto start = std::chrono::high_resolution_clock::now();

并且文档说它返回'代表当前时间的时间点。'

但是我不确定如何在下面的代码中声明，因为我习惯于在函数的开头声明变量，而我不知道将其声明为什么。这里的代码已简化以显示我的意思。我要做什么？ ？

我已经在那儿尝试过自动，但是编译器不允许这样做。

auto orderRecvedTime; --> gives me this error: error: non-static data member declared with placeholder 'auto'

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



class order {
  private:
    string orderID;
    ??? orderRecvedTime;
    char buysell;
    string symbol;
    double price;
    int qty;


  public:

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

};

int main() {


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

    vector<order> thebook;
    string user_order = "";

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



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

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

        order user_order;
        if (orderaction.compare("D") == 0) {
            cout << "you are making a new order."<< endl;
            user_order.newOrder(orderID, buysell,symbol,price,qty);
            thebook.push_back(user_order);
        }  

    }

    return 0;
}

Answer 1

从调试器味精中拉出它，但是如果我这样声明它，它将进行编译。

std :: chrono :: _ V2 :: system_clock :: time_point orderRecvedTime;

Answer 2

std::chrono::high_resolution_clock::time_point orderRecvedTime;