Structure required on left side of . or *

[ggk1298]

Structure required on left side of . or *

  #include<iostream.h>
#include<conio.h>
#include<stdlib.h>
class box
{
 float length,breadth,height;
 public:
 box()
 {
 cout<<"Default Constructor"<<endl;
 length=2;
 breadth=3;
 height=4;
 }
 box(float l,float b,float h)
 {
 cout<<"Parametrized"<<endl;
 length=l;
 breadth=b;
 height=h;
 }
 box(box &ob)
 {
 cout<<"Copy constructor"<<endl;
 length=ob.length;
 breadth=ob.breadth;
 height=ob.height;
 }
 void volume()
 {
 float volume;
 volume=length*breadth*height;
 cout<<"The voume is  "<<volume<<endl;
 }
 ~box()
 {
 cout<<"Destructor invoked";
 }
};

void main()
{
 cout<<"  Program for constructor overloading    "<<endl;
 float a,b,c;
 int ch;
 char rep;
 cout<<"Enter choice "<<endl;
 cout<<"1 Default 2 Parametrized 3 Copy"<<endl;
 cin>>ch;
 while (rep=='y')
 { box gk;
 switch(ch)
   {
   case 1:  box ob1();
	    ob1.volume();
	     break;

   case 2:  {cout<<"Enter length "<<endl;
	     cin>>a;
	     cout<<"Enter breadth "<<endl;
	     cin>>b;
	     cout<<"Enter height "<<endl;
	     cin>>c;
	     box ob2(a,b,c);
	     ob2.volume();
	     }
	     break;

   case 3: {
	    box ob3(gk);
	    ob3.volume();
	    }
	    break;

   default:
	   {
	   cout<<"Invalid choice check!";
	   }
   }
   cout<<"continue?  ";
   cin>>rep;
   }
   getch();
}

[ggk1298]

in line number 55 i get the error. Kindly guide

[Peter87]

box ob1(); declares a function named obj1 that takes no arguments and returns a box.

To fix this problem you only need to remove the parentheses.

[lastchance]

Please use indentation and think about the logic of the main while loop.

#include <iostream>                              // <===== use standard headers
//#include <conio.h>
#include <cstdlib>
using namespace std;                             // <===== either add this line or qualify evrything necessary with std::

class box
{
   float length, breadth, height;
public:
   box()
   {
      cout << "Default Constructor" << endl;
      length = 2;
      breadth = 3;
      height = 4;
   }
   box( float l, float b, float h )
   {
      cout << "Parameterised Constructor" << endl;
      length = l;
      breadth = b;
      height = h;
   }
   box( box &ob )
   {
      cout << "Copy constructor" << endl;
      length = ob.length;
      breadth = ob.breadth;
      height = ob.height;
   }
   void volume()
   {
      float volume;
      volume = length * breadth * height;
      cout << "The volume is " << volume << endl;
   }
   ~box()
   {
      cout << "Destructor invoked" << endl;
   }
};


int main()                                        // <===== int, not void
{
   cout << "  Program for constructor overloading    " << endl;
   float a, b, c;
   int ch;
   char rep;

   rep = 'y';                                     // <===== HAVE TO ADD THIS, OR NOTHING WILL HAPPEN
   while ( rep == 'y' )                       
   { 
      cout << "\nEnter choice " << endl;          // <==== put these 3 lines inside the while loop
      cout << "1 Default 2 Parameterised 3 Copy" << endl;
      cin >> ch;
      box gk;                     
      switch( ch )
      {
      case 1:  
         {                                       // <===== Add brace, because of limited scope of ob1
            box ob1;                             // <===== No brackets
            ob1.volume();
         }
         break;

      case 2:
         {
            cout << "Enter length " << endl;
            cin >> a;
            cout << "Enter breadth " << endl;
            cin >> b;
            cout << "Enter height " << endl;
            cin >> c;
            box ob2( a, b, c );
            ob2.volume();
         }
         break;

      case 3: 
         {
            box ob3( gk );                       // <===== obscure; gk was a no-parameters box
            ob3.volume();
         }
         break;

      default:
         {
            cout << "Invalid choice check!" << endl;
         }
      }
      cout << "Continue (y/n)? ";                // <==== give a choice to reply
      cin >> rep;
   }
// getch();                                      // <==== uncomment if desperate
}