Debug Error! abort() has been called

Question

初学C++,在用VS2017编译书上例子时，报错，请指点！

 #include "stdafx.h"
#include "std_lib_facilities.h"
struct Reading {
    int hour;
    double temperature;
};
int main() {
    cout << "Please input a name" << endl;
    string iname;
    ifstream ist{ iname };
    if (!ist) error("can't open input file name", iname);

    string oname;
    cout << "please input name of output file: ";
    cin >> oname;
    ofstream ost{ oname };
    if (!ost) error("can't open output file", oname);

    vector<Reading>temps;
    int hour;
    double temperature;
    while (ist >> hour >> temperature){
        if (hour < 0 || 23 < hour) error("hour out of range");
        temps.push_back(Reading{ hour,temperature });
        }
    for ( int i = 0; i< temps.size(); ++i)
        ost << '(' << temps[i].hour << ','
        << temps[i].temperature << ")";
}