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whats wrong with my code

bw125bw125 Posts: 10Member
//In class we are learning about private functions in classes and i do
//not understand why i cannot get a value for d

using namespace std;

const double PI = 3.14159;

class Circle{
double C, A, r;
double getC(double C);
double getA(double r, double A);

double d;
double getd(double r);

double Circle::getd(double r){
d = r * 2;
return d;

double Circle::getC(double C){
C = d * PI;
return C;

double Circle::getA(double r, double A){
A = (r * r) * PI;
return A;

int main(int argc, char *argv[]){
Circle x;

double C = 0, A = 0, r;

cout << "Enter the radius: ";
cin >> r;
cout << "The cirumfrence is: " << x.getC(C);
cout << "
cout << "The area is: " << x.getA(r, A);
cout << "



  • LundinLundin Posts: 3,711Member
    The point of making variables private is to prevent anyone from accidently altering them, as well as preventing people to meddle with code that they don't know how it works, or code that they don't even have access too. So you aren't supposed to be able to access "d" from main, you have to use a function like "getd" to get a copy of it.

    This is known as "encapsulation" and is considered very good programming practice.
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