C++: how to set object from member? - c++

Question

I'm pretty new to C++ and I'm trying to make an interactive virtual shop (not like with real money or anything, just something to practice coding, for possible use in a future game). So far I have defined the class and made it so that each object in the class is defined as fruit# where # is its id number (which is used in an array to define its name)
So basically at this point I have created the proper code to turn the user input into the id number of the fruit, but now I need a way to set the values of the fruit "select" to the values of the fruit that id belongs to.
Essentially, they type "banana," which I can use to arrive at the value 0, and the object "fruit0" corresponds to banana. So how do I get from 0 to fruit0? If this is confusing, let me know and I can try to explain better, but I already feel like I'm rambling...
Here's the (relevant parts of the) code:
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
const int fruits=6;
//# of fruits
string names[fruits];
string s;
class fruit {
public:
float weight, price;
int id;
string name;
fruit (float a, float b, string c, int d)
{weight = a; price=b; name=c; names[d]=c;}
};
int main()
{
fruit fruit0 (.5,1,"banana",0);
fruit fruit1 (1.5,3,"pineapple",1);
fruit fruit2 (2,2.5,"coconut",2);
fruit fruit3 (1,1.5,"papaya",3);
fruit fruit4 (4,2,"watermelon",4);
fruit select (0,0,"\0",fruits);
//other, irrelevant code...
}
void ask()
{
cout<<"What would you like to buy? ";
getline (cin,s);
if (s=="select") {dontsell();}
for (i=0;i<fruits;i++)
{if (s==names[i]){select(i);}}
dontsell();
}
void select(int a)
{
//what goes here???
}

Answer 1

I suggest you use std::map<std::string, Fruit>.
You can use the map for storing fruits and their key phrases. It's sort of like a "codename" structure where one value is always associated with another, such as "Banana" to fruit1. Otherwise, I don't really see much of a problem with your question--it's a pretty simple problem which has nice solutions.
You could opt for std::vectors or something, but if you need double vectors that need to be linked by keyword or something, just use std::map.

Answer 2

void ask()
{
cout<<"What would you like to buy? ";
getline (cin,s);
if (s=="select") {dontsell();}
for (i=0;i<fruits;i++)
{
if (s==names[i])
{
// somehow indicate the selected fruit
}
}
dontsell();
}
If I understand correctly, you're asking for advice on how to indicate which fruit object is selected. There are many different ways to do this, but here's one: return the id of the fruit. You also need an array or something to allow you to get the actual fruit object from the id.
int ask() {
// ...
if (s == names[i]) {
return i;
}
// ...
// if nothing matches, return nothing:
return -1;
}
int main() {
fruit fruit_array[fruits] = {
fruit(.5, 1, "banana", 0),
fruit(1.5, 3, "pineapple", 1),
fruit(2, 2.5, "coconut", 2),
fruit(1, 1.5, "papaya", 3),
fruit(4, 2, "watermelon", 4)
};
int selected_id = ask();
if (id > 0) {
std::cout << "You chose " << fruit_array[selected_id].name << '\n';
} else {
std::cout << "You didn't choose anything I recognized.\n";
}
}
Of course, once you do this there are some other changes you would probably want to make. For example there's no reason to have separate arrays names and fruit_array. Here's an example of one way to avoid the duplicate representation of that data.