unit price problem

The word "unitprice" in this part of the program

unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

is giving me problems

The compiler says : "unitprice has not been declared".....then when i declare it its says : "unitprice can not be used as a function"

This thing is crazy , I dont get it.

I copied this program out of a c++ book from college

Thanks

Code:

#include <iostream>
using namespace std;
int main()
{
int diameter_small, diameter_large, unitprice;
double price_small, unitprice_small;
double price_large, unitprice_large;


cout << "Welcome to the pizza consumer union.\n";
cout << "Enter diameter of a small pizza ( in inches): ";
cin >> diameter_small;
cout << "Enter the price of a small pizza: ";
cin >> price_small;
cout << "Enter diameter of a large pizza: (in inches)";
cin >> diameter_large;
cout <<"Enter the price of a large pizza:  ";
cin>> price_large;



unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(2);
cout<<"small pizza:\n";
cout<<"diameter =  " <<diameter_small<<"inches\n"
    <<"Price = $ " <<price_small
    <<" per square inch =$" <<  unitprice_small<<endl
    <<"large pizza:\n";
cout<< "Diameter =  " << diameter_large<< "inches\n";
cout<<"Price = " << price_large;
cout<< "per square inch = " << unitprice_large;
    if (unitprice_large < unitprice_small)
        cout << "The the large one is a better buy\n";
        else
        cout <<"The small one is  better buy\n";
        system("pause");
        return 0;
        
}

double unitprice(int diameter, double price)
{
       const double PI = 3.14159;
       double radius, area;
       
       radius = diameter/static_cast<double>(2);
       area = PI * radius * radius;
       return (price/area);
}

Edited for code tags

 

Please be polite enough to read the "Before you make a query" thread (upper right hand corner of the page).

I refuse to read all that ugly mess, but I read the top part. A function must be declared OR defined (your choice) before it is called. If it is not, it will cause an error in C++. C will assume that it takes one int and returns an int (which would obviously cause errors in your code).

 

that ugly mess was a mistake, some how it multi-copied the program with out me knwoing it.

 

It still needed code tags to preserve the formatting. I've done that for you, but I am not your mama. Please go ahead and read the indicated thread.

The fix for your problem is in my original response.

 

I don't think you understand what Im saying


When i compile the program the way it is I get an error message that says "unitprice has not been declared".

when I declare it such as:

int diameter_small, diameter_large, unitprice;
double price_small, unitprice_small;
double price_large, unitprice_large;
double unitprice;

or

int diameter_small, diameter_large, unitprice;
double price_small, unitprice_small;
double price_large, unitprice_large, unitprice;

or

double unitprice;

unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

Which means that Im declaring it.

Then i compile it , it says "unitprice can not be used as a function"


So if I cant declare it and cant use it as a function after i declre it, then how am i suppose to use it in the program?

Thanks

Code:

#include <iostream>
using namespace std;
int main()
{
int diameter_small, diameter_large, unitprice;
double price_small, unitprice_small;
double price_large, unitprice_large;


cout << "Welcome to the pizza consumer union.\n";
cout << "Enter diameter of a small pizza ( in inches): ";
cin >> diameter_small;
cout << "Enter the price of a small pizza: ";
cin >> price_small;
cout << "Enter diameter of a large pizza: (in inches)";
cin >> diameter_large;
cout <<"Enter the price of a large pizza: ";
cin>> price_large;



unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(2);
cout<<"small pizza:\n";
cout<<"diameter = " <<diameter_small<<"inches\n"
<<"Price = $ " <<price_small
<<" per square inch =$" << unitprice_small<<endl
<<"large pizza:\n";
cout<< "Diameter = " << diameter_large<< "inches\n";
cout<<"Price = " << price_large;
cout<< "per square inch = " << unitprice_large;
if (unitprice_large < unitprice_small)
cout << "The the large one is a better buy\n";
else
cout <<"The small one is better buy\n";
system("pause");
return 0;

}

double unitprice(int diameter, double price)
{
const double PI = 3.14159;
double radius, area;

radius = diameter/static_cast<double>(2);
area = PI * radius * radius;
return (price/area);
}

how do you edit these posts, after i created the first post I couldnt get back to edit it.

 

the code is written in green and black

the part:

unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

is written in green


near the top they have


double unitprice(int diameter, double price) <--- thats the decloration

I didnt see it at all till now because its written i green and there are three lines of notes in greeen also below it so i didnt even see it.

I forgot about how to declare functions. Thats why i kept looking at the int and double declorations after int main(). Then i seen the function decloration among the notes ( all in green)and it all came back to me. Oh yea, oh yea, thats how Im supppose to do it, I forgot. i hadn't opened my book up in about a year and forgot about declorations of functions.

Well , Im back on track now.

sorry about that

thanks

 

things will get well just declare that function before main.
Like this...

Code:

#include <iostream>
using namespace std;

double unitprice(int diameter, double price);

int main()
{
int diameter_small, diameter_large;
double price_small, unitprice_small;
double price_large, unitprice_large;


cout << "Welcome to the pizza consumer union.\n";
cout << "Enter diameter of a small pizza ( in inches): ";
cin >> diameter_small;
cout << "Enter the price of a small pizza: ";
cin >> price_small;
cout << "Enter diameter of a large pizza: (in inches)";
cin >> diameter_large;
cout <<"Enter the price of a large pizza: ";
cin>> price_large;



unitprice_small = unitprice(diameter_small, price_small);
unitprice_large = unitprice(diameter_large, price_large);

cout.setf(ios::fixed);
cout.setf(ios::showpoint);
cout.precision(2);
cout<<"small pizza:\n";
cout<<"diameter = " <<diameter_small<<"inches\n"
<<"Price = $ " <<price_small
<<" per square inch =$" << unitprice_small<<endl
<<"large pizza:\n";
cout<< "Diameter = " << diameter_large<< "inches\n";
cout<<"Price = " << price_large;
cout<< "per square inch = " << unitprice_large;
if (unitprice_large < unitprice_small)
cout << "The the large one is a better buy\n";
else
cout <<"The small one is better buy\n";
system("pause");
return 0;

}

double unitprice(int diameter, double price)
{
const double PI = 3.14159;
double radius, area;

radius = diameter/static_cast<double>(2);
area = PI * radius * radius;
return (price/area);
}

 

This is a function definition:

Code:

double unitprice(int diameter, double price)
{
   const double PI = 3.14159;
   double radius, area;

   radius = diameter/static_cast<double>(2);
   area = PI * radius * radius;
   return (price/area);
}

It will serve as a declaration if it precedes the call. This is also a definition, but it is not a function.

Code:

double unitprice;

So, do you want "unitprice" to be a double or a function? WE don't know. YOU are supposed to know and write the code appropriately.