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passing arrays / updating object arrays

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Duki

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passing arrays / updating object arrays

Sep 4th, 2007

My prof is touching on information hiding, and good programming techniques. He said it's a good idea to keep as much of the user interface (i.e., couts) in main, and then modify object variables through the use of functions.

Here's what I want to do:
I'm starting on a program that lets the user input the type of pizza (hand tossed, pan, deep dish), the size (s, m, l) and the toppings they want.

So far, here's what I've setup in my class:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#pragma once
 
#include <iostream>
using namespace std ;
 
const double SMALL = 10.00
const double MEDIUM = 14.00
const double LARGE = 17.00
const double TOPPING = 2.00
 
class Pizza
{
public:
    void set ( ) ;
    void outputDesc ( ) ;
    double computePrice ( ) ;
private:
    char type ;
    char size ;
    int toppings[7] ;
} ;
#pragma once

#include <iostream>
using namespace std ;

const double SMALL = 10.00
const double MEDIUM = 14.00
const double LARGE = 17.00
const double TOPPING = 2.00

class Pizza
{
public:
    void set ( ) ;
    void outputDesc ( ) ;
    double computePrice ( ) ;
private:
    char type ;
    char size ;
    int toppings[7] ;
} ;

For the toppings, I figured the easiest way is to do a loop of some sort until they're finished inputting toppings (maximum of 7). The reason I'm using an array is because I have to include a function that outputs the object data, including each topping.

My question is this: How can I allow the user to input the toppings they want in main(), and then put that data into the array in my object without creating a temp array for user input?

Last edited by Duki; Sep 4th, 2007 at 9:26 pm.

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Dave Sinkula Dave Sinkula is offline

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long time no c

Re: passing arrays / updating object arrays

Sep 4th, 2007

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Originally Posted by Duki

My prof is touching on information hiding, and good programming techniques.

Good. Then don't do this:

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Originally Posted by Duki

Help with Code Tags

C++ Syntax (Toggle Plain Text)
#pragma once
 
#include <iostream>
using namespace std ;
#pragma once #include <iostream> using namespace std ;

Having the using namespace std basically defeats the purpose of a namespace. And putting it in the header is known to cause problems down the line.

And the #pragma once thing is platform-specific. Include guards are what I would prefer.

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Originally Posted by Duki

My question is this: How can I allow the user to input the toppings they want in main(), and then put that data into the array in my object without creating a temp array for user input?

You could pass parameters to your member functions.

Last edited by Dave Sinkula; Sep 4th, 2007 at 9:47 pm.

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Re: passing arrays / updating object arrays

Sep 4th, 2007

[QUOTE=Duki;428577]
For the toppings, I figured the easiest way is to do a loop of some sort until they're finished inputting toppings (maximum of 7). The reason I'm using an array is because I have to include a function that outputs the object data, including each topping.

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My question is this: How can I allow the user to input the toppings they want in main(), and then put that data into the array in my object without creating a temp array for user input?

Make a member function void add_topping(int topping_number), that adds a topping. Or make an extra array. It's not like it's a big deal, to make an extra array.

And what is 'outputDesc' for? You're having a pizza class that can output its information? That violates the principle you've described. (And what is 'set', too?)

All my posts may be redistributed under the GNU Free Documentation License.

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Re: passing arrays / updating object arrays

Sep 4th, 2007

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Originally Posted by Dave Sinkula

Good. Then don't do this:
Having the using namespace std basically defeats the purpose of a namespace. And putting it in the header is known to cause problems down the line.

so do like std::cout << ?

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And the #pragma once thing is platform-specific. Include guards are what I would prefer.

I don't understand how to use the Include gaurds; could you explain them?

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Originally Posted by Rashakil Fol

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Originally Posted by Duki

For the toppings, I figured the easiest way is to do a loop of some sort until they're finished inputting toppings (maximum of 7). The reason I'm using an array is because I have to include a function that outputs the object data, including each topping.

Make a member function void add_topping(int topping_number), that adds a topping. Or make an extra array. It's not like it's a big deal, to make an extra array.

alright, just wanted to make sure there wasn't an easier way. thanks

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And what is 'outputDesc' for? You're having a pizza class that can output its information? That violates the principle you've described. (And what is 'set', too?)

I'm not sure I understand; why shouldn't I do outputDesc? I need some way of diplaying a list of information that has been input.
Set is the function that sets the values for type/size/toppings

Last edited by Duki; Sep 4th, 2007 at 10:08 pm.

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Re: passing arrays / updating object arrays

Sep 4th, 2007

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Originally Posted by Duki

so do like std::cout << ?

Or using std::cout;

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Originally Posted by Duki

I don't understand how to use the Include gaurds; could you explain them?

Follow that link I posted.

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Originally Posted by Duki

alright, just wanted to make sure there wasn't an easier way. thanks

Early on it's more of an exercise to go through.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include "pizza.h"
 
int main()
{
   pizza::topping toppings[7] = 
   { 
      pizza::sausage, pizza::mushrooms,
      pizza::none, pizza::none, pizza::none, pizza::none, pizza::none,
   };
   pizza mypie(pizza::deep_dish, pizza::medium, toppings);
   std::cout << mypie;
   return 0;
}
 
/* my output
Medium Deep Dish
 Sausage
 Mushrooms
*/
#include <iostream>
#include "pizza.h"

int main()
{
   pizza::topping toppings[7] = 
   { 
      pizza::sausage, pizza::mushrooms,
      pizza::none, pizza::none, pizza::none, pizza::none, pizza::none,
   };
   pizza mypie(pizza::deep_dish, pizza::medium, toppings);
   std::cout << mypie;
   return 0;
}

/* my output
Medium Deep Dish
 Sausage
 Mushrooms
*/

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Duki

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Re: passing arrays / updating object arrays

Sep 4th, 2007

I did follow the link, still didn't make sense

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Re: passing arrays / updating object arrays

Sep 4th, 2007

Help with Code Tags

(Toggle Plain Text)

#ifndef PIZZA_H
#define PIZZA_H

// ...

#endif

As in...

Help with Code Tags

(Toggle Plain Text)

#ifndef PIZZA_H
#define PIZZA_H

#include <ostream>

class pizza
{
public:
   enum type
   {
      hand_tossed, pan, deep_dish
   };
   enum size
   {
      small, medium, large
   };
   enum topping
   {
      none, pepperoni, sausage, mushrooms, green_peppers, canadian_bacon, onions
   };
private:
   type     m_type;
   size     m_size;
   topping  m_topping[7];
public:
   pizza(type type_ = hand_tossed, size size_ = large, topping toppings_[7])
   : m_type(type_), m_size(size_)
   {
      for ( int i = 0; i < sizeof m_topping / sizeof *m_topping; ++i )
      {
         m_topping[i] = toppings_[i];
      }
   }
   friend std::ostream& operator<< (std::ostream& o, const pizza &p);
};

#endif

Each header needs it's own unique #define that you make up.

[edit]The first time you #include "pizza.h", your macro (PIZZA_H in this example) is not #defined, so it gets #defined and the contents #included. Thereafter, subsequent attempts to #include this header will already have the macro (PIZZA_H in this example) #defined, and the contents will be skipped.

Last edited by Dave Sinkula; Sep 4th, 2007 at 11:00 pm.

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Duki

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Re: passing arrays / updating object arrays

Sep 4th, 2007

Oh ok, I still don't quite get it but it's making more sense now.

is there something wrong with this part of my code? I get an error saying arrays of refrences are illegal

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include "prob7.h"
 
void Pizza::set ( char x , char y , int & a[7] )
{
    type = x ;
    size = y ;
    toppings = a ;
}
 
void Pizza::ouputDesc ( int i ) 
{
    cout << endl << "Style:  " << style << endl ;
    cout << "Size:  " << size << endl ;
    cout << "Toppings:  " << flush ;
 
    for ( int x = 0 ; x < i ; x++ )
        cout << toppings [ i ] << ", " << flush ;
}
#include "prob7.h"

void Pizza::set ( char x , char y , int & a[7] )
{
    type = x ;
    size = y ;
    toppings = a ;
}

void Pizza::ouputDesc ( int i ) 
{
    cout << endl << "Style:  " << style << endl ;
    cout << "Size:  " << size << endl ;
    cout << "Toppings:  " << flush ;
    
    for ( int x = 0 ; x < i ; x++ )
        cout << toppings [ i ] << ", " << flush ;
}