Vector iteration and I/O problems

[jpmcfly]

Can someone please give me a tip as to were I am going wrong with my code as I am having problems with iterating through my vector of products. Also can you tell me if I am on the correct lines regards the output of the data to file.

#include <iomanip.h>
#include <string.h>
#include <conio.h>
#include <dos.h>
#include <ctype.h>
#include <vector.h>
#include "derived.h"

main()
{
	ifstream in;
   ofstream out;
   class product product_rec;
   std::vector<product> p;

 	p.push_back( product("Sony PSP",1001,99.99) );
   p.push_back( product("Sony PS3",1002,299.99) );
   p.push_back( product("Xbox",1003,79.99) );
   p.push_back( product("Xbox 360",1004,179.99) );

   in.open("L:\\product.dat",ios::binary);

   while(!in.eof())
   {
   	in.read((char*) & product_rec,sizeof(class product);

      if(in.good())
      {
      	cout << "\n" << setw(24) << product_rec.product_name
         				 << setw(10) << product_rec.product_code
                      << setw(10) << product_rec.unit_price;

         clrscr();
         cout << "File Successfully Written to DAT File";

         out.open("L:\\product.dat",ios::binary|ios::app);

         out << setw(24) << product_rec.product_name;
         out << setw(10) << product_rec.product_code;
         out << setw(10) << product_rec.unit_price;
         out.close();
      }
   }

   std::vector<product>::iterator it;

   for( it = p.begin(); it != p.end(); it++ )
  		cout << *it << endl;
}

I am getting 2 errors:
1 - Is on the in.read((char*) & product_rec,sizeof(class product); where I am told function call missing
2 - Is on the

for( it = p.begin(); it != p.end(); it++ )
  		cout << *it << endl;

where I am told this is an illegal structure operation.

[jsmith]

Your first line isn't even syntactically correct since there are more open parens than close parens.

Your second problem is that product needs to have operator<< defined for it.

[jpmcfly]

Hey again jsmith. Thank you for pointing out the first error I had not noticed it and after adding another bracket the error message has dissapeard.

How do I define the operator ?

[Bazzy]

something like this:

ostream& operator << ( ostream& os, product prod)
{
     //Do you output
     return os;
}

It is best to be declared as product friend

[jsmith]

Either

template< typename charT, typename Traits> friend
std::basic_ostream<charT, Traits>& operator<<(
  std::basic_ostream<charT, Traits>& os, const product& p )
  { return os << ...; }

or as Bazzy said, except pass prod by const reference instead of by value.

[jpmcfly]

#include <iostream.h>
#include <fstream.h>
#include <iomanip.h>
#include <string.h>
#include <conio.h>
#include <dos.h>
#include <ctype.h>
#include <vector.h>
#include "derived.h"

main()
{
	ifstream in;
   ofstream out;
   class product product_rec;
   std::vector<product> p;

 	p.push_back( product("Sony PSP",1001,99.99) );
   p.push_back( product("Sony PS3",1002,299.99) );
   p.push_back( product("Xbox",1003,79.99) );
   p.push_back( product("Xbox 360",1004,179.99) );

   in.open("L:\\product.dat",ios::binary);

   while(!in.eof())
   {
   	in.read((char*) & product_rec,sizeof(class product));

      if(in.good())
      {
      	cout << "\n" << setw(24) << product_rec.product_name
         				 << setw(10) << product_rec.product_code
                      << setw(10) << product_rec.unit_price;

         clrscr();
         cout << "File Successfully Written to DAT File";

         out.open("L:\\product.dat",ios::binary|ios::app);

         out << setw(24) << product_rec.product_name;
         out << setw(10) << product_rec.product_code;
         out << setw(10) << product_rec.unit_price;
         out.close();
      }
   }

   ostream& operator << (ostream& os, const product& p)
  	{
    	return os << p.product_name()<<'\t'
      			 << p.product_code()<<'\t'
                << p.unit_price() << endl;
  	}

}

I have changed the code to your recommendation but am still encountering several errors.

1. Improper use of typedef 'ostream'
2. Improper use of typedef 'ostream'
3. Undefined symbol os
4. Expression syntax
5. Statement missing
6. Compund statement missing

[jsmith]

My version is the more general version of an ostream operator, though in most cases Bazzy's specialization will work.

std::ostream is essentially a basic_ostream instantiated on a char.

To use Bazzy's method,

// Add this inside class product's declaration:
friend ostream& operator<<( ostream& os, const product& p )
{
  // Output whatever you want to output
  //  eg, os << p.product_name;
  return os;
}