constructor is used for initializing the class 
variables.if constructor is not there,variables might be 
taken the garbage values.To avoid garbage 
values ,constructor is used.
        
Example:
 Java:
        int i;
    
        initial value i=0;

C:
        int v;
        v=8823

Constructor is like a method.It can be invoked as soon as 
we create an object for the class.We can overload 
constructor.to call them we need pass parameters in main 
method.