How to pass parameter or call a function?

[matrim]

How do I call a function outside of main or use a parameter to pass a reference?

If my function is:

 
void getData(int& diameter, int& price)
 { 
cout << "Enter in the diameter of the pizza in: " << endl; 
cin >> diameter; cout << "Enter in the the price of the pizza in: " << endl; 
cin >> price; 
 }

How would I call it in main()?

Would it be getData(diameter, price) ?
or some variable = getData(diameter, price) ? I can't figure it out.
or getData(int&, int&) ?
Yes, it was declared at the first part of the program. I get an error saying it expected a primary expression before int?

[dtimes6]

#include <iostream>
using namespace std;

void getData(int& diameter, int& price)
{
cout << "Enter in the diameter of the pizza in: " << endl;
cin >> diameter; cout << "Enter in the the price of the pizza in: " << endl;
cin >> price;
}

int main () {
int diameter;
int price;
getData( diameter, price);
cout << "diameter of the pizza is: " diameter << " price is: " << price << endl;
return 0;
}

[matrim]

Hmm for some reason I put that, and I get:

pizza.cpp
pizza.cpp: In function `int main()':
pizza.cpp:27: warning: unused variable 'diameter'
pizza.cpp:29: error: `diameter' undeclared (first use this function)
pizza.cpp:29: error: (Each undeclared identifier is reported on

And I have:

int diameter;
int price;
getData(diameter, price);
 

What's wrong?

[dtimes6]

Its hard to find where the problem is, can you show me your file?

[vermarajeev]

On my system I get error in this line

cout << "diameter of the pizza is: " diameter << " price is: " << price << endl;

so I have used this

cout << "diameter of the pizza is: " <<diameter << " price is: " << price << endl;

[dtimes6]

right that's my fault!

[matrim]

Price is part of an equation, so I don't think that will work. Here's the whole file:

#include <iostream>
 
using namespace std;
 
char pizzaType;
void getData(int length, int width, int price);
void getData(int diameter, int price);
double computeUnitCost(int diameter, int price);
double computeUnitCost(int length, int width, int price);
 
int main()
{
        bool okay = true;
        do {
        cout << "Please enter in the type of pizza: " << endl;
        cout << "r - a round pizza" << endl;
        cout << "s - a square pizza" << endl;
        cin >> pizzaType;
 
        cin.ignore(80, '\n');
 
        okay = (pizzaType == 'r' || pizzaType == 's');
 
            cout << "\nYou entered an invalid pizza type!" << endl;
        }while(!okay);
        if (pizzaType == 'r')
        int diameter;
        int price;
        void getData();
        cout << "The price per square inch for this pizza is " << getData(diameter, price) << endl;
    //return 0;
        if (pizzaType == 's')
 
        int squarePrice = getData(int& length, int& width, int& price);
        cout << "The price per square inch for this pizza is " << getData << endl;
}
 
void getData(int& length, int& width, int& price)
    {
 
        cout << "Enter in the length of the pizza: " << endl;
        cin >> length;
        cout << "Enter in the width of the pizza: " << endl;
        cin >> width;
        cout << "Enter in the price of the pizza: " << endl;
        cin >> price;
        double computeUnitCost(int&, int&);
    }
void getData(int& diameter, int& price)
    {
        cout << "Enter in the diameter of the pizza in: " << endl;
        cin >> diameter;
        cout << "Enter in the the price of the pizza in: " << endl;
        cin >> price;
    }
 
double computeUnitCost(int diameter, int price)
    {
        int roundCost = diameter / price;
    cout << "The price per square inch for this pizza is: " << roundCost << endl;
    return roundCost; // not sure if i need to return this or if its the right way
}
 
double computeUnitCost(int length, int width, int price)
    {
        int squareCost = ((length * width))/ price;
    cout << "The price per square inch for this pizza is: " << squareCost << endl;
        return squareCost; // not sure if this is the right way to return it
 
    }

[dtimes6]

remember to pass by reference if you want a return value be put into the referenced object. use const reference if you want a value that is never changed in your function scope.

you have to change:

void getData(int length, int width, int price);
void getData(int diameter, int price);

void getData(int& length, int& width, int& price);
void getData(int& diameter, int& price);

[tyreld]

Your function prototypes have to match your function declarations. In the code you posted you have neglected to include the reference operator "&" in your parameter lists.

[matrim]

woops. I had them there originally, then took them out for some reason. I think i messing around with using string instead of void.

Here's what I need to accomplish:

Your program should include

1. A function named getData( )that gets all of the user input for a round pizza. For a round pizza it will ask for the diameter of the pizza and its price. Each piece of data entered by the user must be validated to ensure that it is a non-zero, positive value. If a value is zero or negative, tell the user that the input is invalid and go back and ask for that data to be input again. Somehow, this function must store the values it gets from the user where they can be accessed by other parts of the program. You cannot use global variables! The return type of the function is void.
2. Another function named getData( )that gets all of the user input for a square pizza. For a square pizza it will ask for the length and width of the pizza and its price. Each piece of data entered by the user must be validated to ensure that it is a non-zero, positive value. If a value is zero or negative, tell the user that the input is invalid and go back and ask for that data to be input again. Somehow, this function must store the values it gets from the user where they can be accessed by other parts of the program. You cannot use global data. The return type of the function is void.
3. A function named computeUnitCost( ) that takes the diameter of a round pizza and its price as parameters, and returns the cost of 1 square inch of that pizza.
4. Another function named computeUnitCost( ) that takes the length and width of a rectangular pizza and its price, and returns the cost of 1 square inch of that pizza. Note that the function computeUnitCost( ) is overloaded.