5 replies to this topic

[Apprentice123]

What is and how works operator in c++ ?

operator <<

operator >>

[John]

Since operators can be overloaded, can you at least provide the context in which they are used? They are most likely the extraction and insertion operators
operator>> - C++ Reference

[abzero]

Or bitshift operators, either left or right

[Apprentice123]

John said:

Since operators can be overloaded, can you at least provide the context in which they are used? They are most likely the extraction and insertion operators
operator>> - C++ Reference

My question is when they appear in a class. Example:

class Example
{
    const Example& operator << (int variable);
    const Example& operator >> (int variable);
}

[Flying Dutchman]

In your code they are overloaded so they do whatever code you tell them to do.

[mnirahd]

Hi,

A class can overload insertion & extraction operators in order to get/output and set its private data. For example, you have a following class

class Employee

{

  private:

      string m_sEmployeeName; //string to keep employee name

      int      m_iEmployeeID; //int to keep employee id

      double m_dEmployeeSalary; //a double to keep employee salary

 }

Suppose that you want to show an object to Employee Object data to console. Normally, we can use 'cout<<variable' to output to console: but in case of user-defined data types like class, we need to overload extraction operator for that class.

How to Overload '<<' For a class

Suppose for Employee class that we have defined above, we want to overload << operation. For this we define a friend function for this class

class Employee

{

  private:

      string m_sEmployeeName; //string to keep employee name

      int      m_iEmployeeID; //int to keep employee id

      double m_dEmployeeSalary; //a double to keep employee salary

  public:

       Employee(string n, int i, double s): m_sEmployeeName(n), m_iEmployeeID(i), m_dEmployeeSalary(s)

{

}

      //a friend function that overloads << operation for our class

       friend ostream& operator<< (ostream &out, Employee &employee);

};


ostream& operator<< (ostream &out, Employee &employee)

{

	    // Since operator<< is a friend of the Employee class, we can access

	    // Employee's members directly.


            out<<"Employee Name "<<employee.m_sEmployeeName<<endl;

            out<<"Employee ID "<<employee.m_iEmployeeID<<endl;

            out<<"Employee Salary "<<employee.m_dEmployeeSalary<<endl;


	    return out;

}

When overload '<<' is called

Since we have overload << for our class employee. we can use it to extract the values from an object of class employee

//in main function


int main()

{

   Employee employee("Munir", 1045, 6000.00);

   cout<<employee;[B][COLOR="SeaGreen"] //This is the place when overload function for << for Employee class is called[/COLOR][/B]

}

The following would be the output

Employee Name Munir

Employee ID 1045

Employee Salary 6000

I hope this helps!

Munir