Structs problem

[sh129951]

I think i am getting confused with passing structs and functions all in the same

When I run through the program (it compiles), the functions that add coins do not add, but rather just replace an old value with a new one.

#include <cstdlib>
#include <iostream>

using namespace std;

struct coinbox
{
       int quarters;
       int dimes;
       int nickels;
       int pennies;
};

void initialize (coinbox& c);
void add_quarters (coinbox& c, int quarters);
void add_dimes (coinbox& c , int dimes);
void add_nickels (coinbox& c, int nickels);
void add_pennies (coinbox& c, int pennies);
void make_change (coinbox& c, int amount);
void show (coinbox c);



int main(int argc, char *argv[])
{
   
    
    char input;
    coinbox  c,q,d,n,p;
    
  
    initialize(c);
    
     bool coins = true;
     while (coins==true)
     {
    
    cout << "Enter s (show coinbox), q (add quarters), d (add dimes)\n n (add nickels), p (enter pennies), c (make change), e(end): ";
    cin >> input;
    
    
    
    if (input=='s')
        {
        show (c);
        }
        
    if (input=='q')
       {
       add_quarters (c, q.quarters);
       }
    
    if (input=='d')
       {
       add_dimes (c, d.dimes);
       }
       
    if (input=='n')
       {
       add_nickels (c, n.nickels);
       }
       
    if (input=='p')
       {
       add_pennies (c, p.pennies);
       }

    
    
       
    
    if(input=='e')
    {
     coins=false;
    
    
    system("PAUSE");
    return EXIT_SUCCESS;
}
   
}

}

void initialize (coinbox& c)
{
     c.dimes=0;
     c.quarters=0;
     c.nickels=0;
     c.pennies=0;
     
}

void add_quarters (coinbox& c, int quarters)
{
     
     cout << "Enter the number of quarters to add: ";
     cin >> c.quarters;
     cout << endl;
     
     }
     
     
void add_dimes (coinbox& c , int dimes)
{
     cout << "Enter the number of dimes to add: ";
     cin >> c.dimes;
     cout << endl;
     
     
     }
     
     
void add_nickels (coinbox& c, int nickels)
{
     cout << "Enter the number of nickels to add: ";
     cin >> c.nickels;
     cout << endl;
     
     
     }
     
     
void add_pennies (coinbox& c, int pennies)
{
     cout << "Enter the number of pennies to add: ";
     cin >> c.pennies;
     cout << endl;
     
     }
     
     
void make_change (coinbox& c, int amount)
{
     
     }


void show (coinbox c)
{
     cout << "\nQuarters: "<< c.quarters;
     cout << "\nDimes: "<< c.dimes;
     cout << "\nNickels: " << c.nickels;
     cout << "\nPennies: " << c.pennies;
     cout << endl;
     cout << endl;
     
     }

[Stewbond]

I'm a little confused regarding what these functions are supposed to do.

void add_pennies (coinbox& c, int pennies)
{
    cout << "Enter the number of pennies to add: ";
    cin >> c.pennies;
    cout << endl;     
}

Decide on only ONE thing for a function to do. If you want the user to input a value and add that value to a coinbox do this:

void add_pennies (coinbox& c)
{
    int newPennies;
    cout << "Enter the number of pennies to add: ";
    cin >> newPennies;
    c.pennies += newPennies;
}

if you want to add pennies from an argument to a coinbox, do this:

void add_pennies (coinbox& c, int pennies)
{
    c.pennies += pennies;
}

if you want to dump one coinbox into another, do this:

void dump_box(coinbox& dest, coinbox source)
{
    dest.quarters += source.quarters;
    dest.dimes    += source.dimes;
    dest.nickels  += source.nickels;
    dest.pennies  += source.pennies
}

On some compiler settings, an unreference parameter (like parameter 2 of add_pennies) will give a warning. That's because it's poor design. You don't want to force a user of a function to give data that isn't used/needed. They may need to go to some serious calculations to get you that data. In addition, it isn't clear what it is intended for anyways.