Determine Gross wage using class

I am trying to make a program that computes gross by using a class and three functions. When I try to run it, it gives me this error I think something is wrong with my set function and my int main function, any help would be appreciated.

Code:

---

#include <iostream>
using namespace std;

double payRate;
int hours;

class Employee
{
 public:
 void set(double payRate, int hours);
 double pay();
 void display();

 private:
 int hours;
 double payRate;
 double Gross;
};

int main()
{
 Employee wage;
 cout << "What is the pay rate:";
 cin >> payRate;
 cout << "How many hours worked:";
 cin >> hours;
 wage.set(payRate, hours);
 wage.display();
}

void Employee::set(double payRate, int hours)
{
 cin >> payRate;
 cin >> hours;
}

double Employee::pay()
{
 return Gross= payRate* hours;
}

void Employee::display()
{
 cout << "The Gross wage is: " << Gross;
}

---

>> When I try to run it, it gives me this error

What error? And why are you reading the input twice (once from main and then from set())?

Code:

---

#include <iostream>
using namespace std;

double payRate;
int hours;

class Employee
{
 public:
 void set(double payRate, int hours);
 double pay();
 void display();

 private:
 int hours;
 double payRate;
 double Gross;
};

int main()
{
 Employee wage;
 cout << "What is the pay rate:";
 cin >> payRate;
 cout << "How many hours worked:";
cin >> hours;
 wage.set(payRate, hours);
 wage.display();
}

void Employee::set(double payRate, int hours)
{
 cin >> payRate;
 cin >> hours;
}

double Employee::pay()
{
 return Gross= payRate* hours;
}

void Employee::display()
{
 cout << "The Gross wage is: " << Gross;
}

---

Why do you read in "payRate" and "hours" in main and again in the "set" function? You don't need to read those values in main; just use the set function.

not to mention you can't just use them without initializing them.