02_Constant Member Function

Const Member functions

Defination

Tese are member functions of class which allow only memory reading.It simply means we can not change any data member of class either const or non-const data member in Const member functions.The can be accessed by both const object and non-const object.

Note

constructors are also special member functions of class but it is not allowed to make constructors const functions.

Example code

#include<iostream>
using namespace std;

class Student
{
	String name;
	const int Id = 1;

public:

	//-----Getters/Accessors----
	string getName() const
	{
		//Here if you try to modify data member name,it will cause error although it is non-const
		// like:
		// name="Waleed";
      return name;

	}
	int getId() const
	{
		//Here if you try to modify data member Id,it will cause error
		// like:
		// Id=9;
      return Id;

	}

};
int main()
{
	Student student_1;
	Student const  student_2;

	//Accessing constant function by Non const-object
	student_1.getId();

	//Accessing constant function by const-object
	student_2.getId();

}