tell me errors and decode with explanation

Question

#include<iostream>
using namespace std;
namespace BMW
{
    int Car_model;
    string Car_name;
    void display()
    {
        cout<<"enter the Model of a Car";
        cin>>Car_Model;
        cout<"enter the name of a Car";
        cin>>Car_name;
        cout<"name of Car ="<<Car_name;
        cout<<"Model of Car = "<<Car_Model;
    }
}
namespace Supra
{
    int Car_Model;
    string Car_name;
    void diplay()
    {
        cout<<"enter the Model of a Car";
        cin>>Car_Model;
        cout<<"enter the Car_name";
        cin>>Car_name;
        cout<<"name of a Car ="<<Car_name;
        cout<<"Model of a Car ="<<Car_Model;
    }
}

Answer 1

You have a mixed casing of Car_Model and Car_model. Most programming languages, including C++ is case sensitive, so stick with one or the other, as they are two different identifiers.

The operator for a stream to take data is << (two less than) not a single one, so check your "cin<" code as they are wrong.

After this, your code should compile, but...

... you have no main function, so your code will not run.

... and I have never seen such a design in my life. Why would you have these global variables (Car_name and Car_model) in namespaces (BMW and Supra)? They are not particularly practical. Usually, classes should be employed to hold data that belongs together.

Try this instead:

#include <iostream>
#include <string>

class Car
{
private:
    int _model;
    std::string _make;

public:
    Car(std::string make, int model)
    {
        _model = model;
        _make = make;
    }
    
    void Display() const
    {
        std::cout << "Make: " << _make << "; Model: " << _model << std::endl;    
    }
    
    int GetModel() { return _model; }
    std::string GetMake() { return _make; } 
};

int main()
{
    Car bmw("BMW iX", 2019);
    Car toyota("Toyota GR Supra", 2020);
    bmw.Display();
    toyota.Display();
    return 0;
}