如何使用File I / O将函数输出到文本文件中

Question

现在我有一个名为void的{​​{1}}函数。我想将此函数中的所有内容显示为文本文件。以下是我的代码，但它不起作用。

displayAllCars(Cars)

错误是＆＃34;不匹配运营商＆lt;＆lt;在salesAnalysis＆＃34;

Answer 1

ostream & displayAllCars(ostream & ostr, vector<Vehicle*>& cars)
{
    for(int i = 0; i < cars.size(); i++)
    {
        ostr << i+1 <<". ";
        cars[i]->display(ostr);
        ostr << endl;
    }
}

ofstream salesAnalysis("salesAnalysis.txt");
displayAllCars(salesAnalysis, cars);
salesAnalysis << "Total Sales for the Company(RM): " << totalSales << endl

Answer 2

您需要重载运算符＆lt;＆lt; ：

ostream& operator << (ostream &os, const vehicle &vc) {
    vc.display(os);
    return os;
}

ostream& operator << (ostream &os, const vector<vehicle*> &vc) {
    for(int i = 0; i < vc.size; ++i) {
        os << *vc[i] << " "; // after *vc[i] some separator or std::endl
    }
    return os;
}