CPP Constructor

Constructor

  • A class constructor is a special member function of a class that is executed whenever we create new objects of that class.
  • A constructor will have exact same name as the class.
  • it does not have any return type at all, not even void.
  • Constructors can be very useful for setting initial values for certain member variables.

Syntax:

class_name () 
{ Constructor Definition }

Following example explains the concept of constructor:

Example:

#include <iostream>

class Line
{
 public:
 void setLength( double len );
 double getLength( void );
 Line(); // This is the constructor

private:
 double length;
};
// Member functions definitions including constructor
Line::Line(void)
{
 cout << "Object is being created" << endl;
}
void Line::setLength( double len )
{
 length = len;
}
double Line::getLength( void )
{
 return length;
}
// Main function for the program
void main( )
{
 Line line;
 // set line length
 line.setLength(6.0);
 cout << "Length of line : " << line.getLength() <<endl;
 getch();
}

Output:

Object is being created
Length of line : 6


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Constructor and Destructor