Question

如何初始化dvd1？

C:\Users\SuperUser\Google Drive>g++ -o a Question1.cpp

Question1.cpp：在函数＆＃39; int main（）＆＃39;：

Question1.cpp：39：76：错误：在C ++ 98＆＃39; dvd1＆＃39;必须由构造函数初始化，而不是由＆＃39; {...}＆＃39;
初始化
dvd dvd1 = {＆＃34; Zombie＆＃34;，＆＃34; BBC＆＃34;，＆＃34; James＆＃34;，＆＃34;英语＆＃34;，＆＃34; Alw＆＃34 ;，2012,20170601,20170630};

#include <iostream>
#include <string>

using namespace std;

class dvd
{
    string movieName,movieProdComp,movieLeadActor,movieLanguage,renterName;
    int releaseYear,rentDate,returnDate;
    public:

        dvd(string mn,string mpc,string mla,string ml, string rn,int ry,int rd,int retd);
        void print();
};

dvd::dvd(string mn,string mpc,string mla,string ml, string rn, int ry,int rd,int retd){
    movieName=mn;
    movieProdComp=mpc;
    movieLeadActor=mla;
    movieLanguage=ml;
    renterName=rn;
    releaseYear=ry;
    rentDate=rd;
    returnDate=retd;
}

void dvd::print(){
    cout<<"Movie:"<<movieName<<endl;
    cout<<"Production:"<<movieProdComp<<endl;
    cout<<"Starring:"<<movieLeadActor<<endl;
    cout<<"Language:"<<movieLanguage<<endl;
    cout<<"Rented By:"<<renterName<<endl;
    cout<<"Released:"<<releaseYear<<endl;
    cout<<"Rent Date:"<<rentDate<<endl;
    cout<<"Return Date:"<<returnDate<<endl;
}

int main(){
    dvd();
    dvd dvd1 = {"Zombie","BBC","James","English","Alw",2012,20170601,20170630};
    dvd1.print();
}

Answer 1

dvd是非aggregate type，无法使用支撑的初始化程序进行初始化，直到支持list initialization的C ++ 11。（更准确地说，您尝试做的是复制列表初始化。）

对于C ++ 98，您可以编写

dvd dvd1 ("Zombie","BBC","James","English","Alw",2012,20170601,20170630);
dvd dvd1 = dvd("Zombie","BBC","James","English","Alw",2012,20170601,20170630);

在C ++ 98中，只有当dvd dvd1 = {...};为聚合类型时才可以使用aggregate initialization;对于这种情况，dvd具有用户定义的构造函数，然后不是。

Answer 2

这称为list initialization，对于非聚合类型，它仅在C ++ 11中受支持：

dvd dvd1 = {"Zombie","BBC","James","English","Alw",2012,20170601,20170630};

对于C ++ 98，你可能想稍微改一下，像往常一样调用构造函数：

dvd dvd1("Zombie","BBC","James","English","Alw",2012,20170601,20170630);

在C ++ 98＆＃39; dvd1＆＃39;必须由构造函数初始化，而不是由＆＃39; {...}＆＃39;

2 个答案: