Error to use of static and static function in C++

i am beginner in programming, start C++ one weak ago. i have problem to use of my static variable. i read about use of static variable in various same question but i understand just this Car::countOfInput;. from below post:

1. How do I call a static method of another class




2. C++ Static member method call on class instance




3. How to call static method from another class?

this is my code:

#include 
#include 
#include 

using namespace std;


class Car{
    private:
        static int countOfInput;
        char   *carName;
        double carNumber;
    public:
        Car() {
            static int countOfInput = 0;
            char carName = {'X'};
            double carNumber = 0;

        }

        void setVal(){
            double number;

            cout << "Car Name: ";
            char* str = new char[strlen(str) + 1];
            cin>>str;
            strcpy(carName, str);


            cout << endl << "Car Number: ";
            cin >> number; cout << endl;
            carNumber = number;

            Car::countOfInput += 1;
       }

       friend void print(){
            if(Car::countOfInput == 0){
                cout << "Error: empty!";

                return;
            }
            cout << "LIST OF CarS" << endl;
            cout << "Car Name: " << carName << "\t";
            cout << "Car Number: " << carNumber << endl;
      } const

      void setCarNumber(int x){carNumber = x;}
      int  getCarNumber(){return carNumber;}


      void setcarName(char x[]){strcpy(carName, x);}
      char getcarName(){return *carName;}

      int getCountOfInput(){return countOfInput;}
      void setCountOfInput(int x){countOfInput = x;}
};

int main(){
    Car product[3];
    product[0].setVal();

    product[0].print();

    getch();
    return 0;
}

when i run this:

F:\CLion\practise\main.cpp: In function 'void print()':

F:\CLion\practise\main.cpp:10:13: error: invalid use of non-static data member 'Car::carName'
char *carName;
^

F:\CLion\practise\main.cpp:40:33: error: from this location
cout << "Car Name: " << carName << "\t";
^

F:\CLion\practise\main.cpp:11:12: error: invalid use of non-static data member 'Car::carNumber'
double carNumber;
^

F:\CLion\practise\main.cpp:41:35: error: from this location
cout << "Car Number: " << carNumber << endl;
^

F:\CLion\practise\main.cpp: In function 'int main()':

F:\CLion\practise\main.cpp:57:16: error: 'class Car' has no member named 'print'
product[0].print();

I use CLion, Thanks in advance.

Answer

The variable declaration inside Car() are local variables, not initializations of the member variables. To initialize the member variables, just do this (it's a member initializer list):

Car() : carName("X"), carNumber(0) {}

and put the definition of countOfInput outside the class in a .cpp file (in global scope):

int Car::countOfInput = 0;

(If you want to reset countOfInput to 0 every time the Car() constructor is called, you can do that in the constructor body: countOfInput = 0;)