C++ Class
- Class is a collection of data and function under a single name.
- Class is similar to function with only difference that it can have functions besides data items.
- It is a blueprint for objects.
- Class definition starts with the keyword class followed by the class name and ends with a semicolon (;).
- The primary purpose of a class is to hold data/information.
Syntax:
{
Access specifier:
Data members;
Member functions(){}
};
Example
class employee
{
public:
int empid;
string empname;
float salary;
};
C++ Object
- Object is an instantiation of a class.
- It has same relationship to class as variable has to the data type.
- Object is created from a class.
- It is exactly the same sort of declaration that we do for the variables of different data types.
Syntax:
class_name variable_name;
Example
Consider the above Employee class. Object for Employee class can be defined as:
Employee e;
Here, object e of Employee class is defined.
Example : Following example demonstrates the working of Objects & Class in C++
#include <iostream>
using namespace std;
class Employee
{
private:
int empid;
string empname;
float salary;
public:
int emp_details()
{
empid=100;
empname="ABC";
salary=10000.0;
}
int show()
{
cout<<"Employee Id : "<<empid<<endl;
cout<<"Employee Name : "<<empname<<endl;
cout<<"Employee Salary : "<<salary<<endl;
}
};
int main()
{
Employee e;
e.emp_details();
e.show();
return 0;
}
Output:
Employee Id : 100
Employee Name : ABC
Employee Salary : 10000
- In the above program, there are three data members empid, empname & salary. Two member functions emp_details() & show() are defined under Employee class.
- Object e of the Employee class is declared. Function emp_details() for the object e is executed using code e.emp_details() which includes details of the employee. Then, function show() for the object e is executed which displays details of the employee and returns it to the calling function.
Class v/s Structure
Following is the difference between Class and Structure:| Class | Structure |
|---|---|
| Class is a reference type. | Structure is a value type. |
| In class, object is created on the heap memory. | In structure, object is created on the stack memory. |
| It supports inheritance. | It does not support inheritance. |
| It includes all types of constructors and destructors. | It includes only parameterized constructors. |
| Object can be created using new keyword. For eg. Test t = new Test(); | Object can be created without using the new keyword. For eg. Test t; |
| The member variable of class can be initialized directly. | The member variable of structure cannot be initialized directly. |
