#include <iostream>
using namespace std;

class car{

string owner;
string car_num;
string issue_date;

car(string o, string cn, string id)
{
    owner = o;
    car_num  = cn;
    issue_date = id;
}

void getInfo()
{
    cout << "Car's Owner's Name : " << owner << endl;
    cout << "Cars' Number : " << car_num << endl;
    cout << "Car's Issue Date : " << issue_date << endl;
}

};

int main()
{
    
    int n;
    cout << "Enter total number of cars stored in your garage : \n";
    cin >> n;
    car c1[n]; //incomplete code due to the issue


    return 0;
}

Here I want to take the total car numbers from user. And also want to take the car properties from user by using a loop. But how Can I do that while using a constructor?

CodePudding user response：

My advice is not to over use the constructor. It supposed to construct, and really should only construct. In your case, you don't even really need a constructor. Instead add a new function to do initialization. Traditional is to use an operator >> which is often an external function.
As for the loop...

car c1[n]; //incomplete code due to the issue

is not legal C (although it's allowed in C, and many compilers that are also C compilers)
It's better to use a vector. So...

    vector<car> c1(n);
    for (auto& c : c1) 
       cin >> c;

An advanced technique is to use a istream iterator, which will allow you to use algorithms like std::copy, calling the input operator for each member of the vector. However, it's really not required, just a "nicety"

CodePudding user response：

Use pointer array instead.e.g.

car* c1[n];

//incomplete part
for(int i = 0; i < n; i  ){
    //take input and process
    c1[i] = new car(//put processed inputs here);
    }

PS: I feel like I made a mistake somewhere but can't test it now. If it doesn't work, put a comment here.

CodePudding user response：

You can use loop with std::cin, likefor(int i=0;i<n; i){std::cin<<num;}. The 'n' I mentioned in the code can also be assigned by std::cin

int n;
std::cin>>n;
car* cars=new car[n];
for(int i=0;i<n;  i)
{
   std::getline(cars[i].owner,std::cin);
   // and something other you'd like to do, like to test its validity
}

CodePudding user response：

car c1[n]; //incomplete code due to the issue

In fact, you have 2 issues here:

1. Variable-Length Arrays (VLA) are not allowed in standard C . They are optionally allowed in standard C, and are supported by some C compilers as an extension.
2. You can't have an array of objects w/o default constructor (unless you fully initialize it).

Assuming you don't want to change the class (other than insert public: after the data members), the modern solution should use std::vector:

    std::vector<car> c;

    //incomplete part
    for(int i = 0; i < n; i  ){
        std::string owner, car_num, issue_date;
        //TODO: get the strings from the user here ...
        c = c.emplace_back(owner, car_num, issue_date);
        }

CodePudding user response：

#include <iostream>
using namespace std;

class car{
public:
string owner;
string car_num;
string issue_date;

void cars(string o, string cn, string id)
{
    owner = o;
    car_num  = cn;
    issue_date = id;
    getInfo();
}

void getInfo()
{
    cout << "Car's Owner's Name : " << owner << endl;
    cout << "Cars' Number : " << car_num << endl;
    cout << "Car's Issue Date : " << issue_date << endl;
}

};

int main()
{
    
    int n;
    string a,b,c;
    cout << "Enter total number of cars stored in your garage : \n";
    cin >> n;
    car cas[n]; //incomplete code due to the issue
    for(int i=0;i<n;  i)
    {
     cout<<"value1:";
     cin>>a;
     cout<<"value2:";
     cin>>b;
     cout<<"value3:";
     cin>>c;
     cas[i].cars(a,b,c);
    }

    return 0;
}