Can anyone tell me how to improve this program?

[evertangel]

Can anyone help me to improve this program? So please feel free to correct me or tell me what I'm doing wrong.
Thanks!

#include <iostream>
#include <string>

using namespace std;

int multiply (int a,int b)
{
int r;
r=a*b;
return(r);
}
int subtract (int a,int b)
{
int r;
r=a-b;
return (r);
}

void beverages()
{
cout<<"Beverages"<<endl<<endl;
cout<<"Coke - 12"<<endl;
cout<<"Sprit - 12"<<endl;
cout<<"Coffee - 5"<<endl;
}
void snacks()
{
cout<<"Snacks"<<endl;
cout<<"Sandwich - 15"<<endl<<endl;
cout<<"Hamburger - 15"<<endl;
cout<<"Spagetti - 15"<<endl;
}

int main()
{
int drinks[2];
drinks[0]=12;
drinks[1]=12;
drinks[2]=5;

int snack[2];
snack[0]=15;
snack[1]=15;
snack[2]=15;

int choice;
int choice_2;
int cost;
int quantity;
int total=0;
int cash;
int change;
char more;

again:
snacks();
cout<<endl;
beverages();
cout<<endl;
cout<<"Choice:"<<endl;
cout<<"1. Snacks"<<endl; cout<<"2. Beverages"<<endl<<endl;
cout<<"Please place your order:";
cin>>choice;


while (true)
{
    if (choice==1)
    {
    system("cls");
    snacks();
    cout<<endl;
    cout<<"Select your choice:";
    cin>>choice_2;
        if (choice_2==1)
        {
      cout<<"Quantity:";
      cin>>quantity;
      cout<<endl;
      cout<<"Cost:";
      cost=multiply(snack[0],quantity);
      total=total+cost;
      cout<<cost<<endl;
      break;
      }else if (choice_2==2)
      {
      cout<<"Quantity:";
      cin>>quantity;
      cout<<endl;
      cout<<"Cost:";
      cost=multiply(snack[1],quantity);
      total=total+cost;
      cout<<cost<<endl;
      break;
      }else if (choice_2==3)
      {
      cout<<"Quantity:";
      cin>>quantity;
      cout<<endl;
      cout<<"Cost:";
      cost=multiply(snack[2],quantity);
      total=total+cost;
      cout<<cost<<endl;
      break;
      }
   }
   else if (choice==2)
       {
      system("cls");
        beverages();
        cout<<endl;
        cout<<"Select your choice:";
        cin>>choice_2;
      if (choice_2==1)
      {
      cout<<"Quantity:";
      cin>>quantity;
      cout<<endl;
      cost=multiply(drinks[0],quantity);
      total=total+cost;
      cout<<"Cost:";
      cout<<cost<<endl;
      break;
      }else if (choice_2==2)
      {
      cout<<"Quantity:";               
      cin>>quantity;
      cout<<endl;
      cost=multiply(drinks[1],quantity);
      total=total+cost;
      cout<<"Cost:";
      cout<<cost<<endl;
      break;
      }else if (choice_2==3)
      {
      cout<<"Quantity:";
      cin>>quantity;
      cout<<endl;
      cost=multiply(drinks[3],quantity);
      total=total+cost;
      cout<<"Cost:";
      cout<<cost<<endl;
      break;
      }
   }
}

cout<<"Do you want to try again?(y/n)";
cin>>more;
if (more=='y'||more=='Y')
{
system ("cls");
goto again;
}else if (more=='n'||more=='N')
{

cout<<"The total amount you bought is "<<total<<endl;
cout<<"Please enter payment:";
cin>>cash;
cout<<endl;
do
{
system ("cls");
cout<<"Sorry the amount you entered is incorrect"<<endl;
cout<<"Please try again"<<endl;
cout<<endl;
cout<<"The total amount you bought is "<<total<<endl;
cout<<"Please enter payment:";
cin>>cash;
cout<<endl;
}while (cash>total);

change=subtract(cash,total);
cout<<"Your change:"<<change<<endl;

}
cout<<"...Please press ENTER..."<<endl;
cin.ignore(2);
return 0;
}

This part of the code still has problems so if anyone has any opinions I'd be very thankfull.

cout<<"Do you want to try again?(y/n)";
cin>>more;
if (more=='y'||more=='Y')
{
system ("cls");
goto again;
}else if (more=='n'||more=='N')
{

cout<<"The total amount you bought is "<<total<<endl;
cout<<"Please enter payment:";
cin>>cash;
cout<<endl;
do
{
system ("cls");
cout<<"Sorry the amount you entered is incorrect"<<endl;
cout<<"Please try again"<<endl;
cout<<endl;
cout<<"The total amount you bought is "<<total<<endl;
cout<<"Please enter payment:";
cin>>cash;
cout<<endl;
}while (cash>total);

change=subtract(cash,total);
cout<<"Your change:"<<change<<endl;

}

[firedraco]

Your functions are pretty useless to be honest, subtract and add are a waste of time, and the printing ones are kind of worthless IMHO. You are going 1 too many on your arrays (int something[2] has 2 elements, [0] and [1] ONLY).

Use more indentation, your code is quite difficult to read (at least your main function is).

Don't use goto...it's not needed here. Use a loop. And add some useful functions, like a "Select your choice" function or something.

[Danny Toledo]

Make it actually give me a snack and/ or a beverage.