CODEWITHSUNDEEP
c++objectpass-by-reference
Johnathan
Johnathan

Reputation: 1917

Can't pass a constant object by reference

I am practicing class declaration/implementation/passing object by reference. Here is my code for my main class, header file, and other class:

//Header file (Circle2.h)
#ifndef CIRCLE_H
#define CIRCLE_H

class Circle{
    private:
        double radius;

    public:
        Circle();
        Circle(double newRadius);
        double getArea() const;
        double getRadius() const;
        void setRadius(double newRadius);
};
#endif

//Main class (PassObjectByReference.cpp)
#include <iostream>
#include "Circle2.h"
using namespace std;

void printCircle(const Circle &c){
    cout << "The area of the circle of " << c.getRadius() << " is " << c.getArea() << endl;
}

int main(){
    Circle myCircle(5.0);
    printCircle(&myCircle);

    return 0;
}

//Other class (Circle2.cpp)
#include "Circle2.h"

Circle::Circle(){
    radius = 1;
}

Circle::Circle(double newRadius){
    radius = (newRadius >= 0) ? newRadius : 0;
}

double Circle::getRadius() const{
    return radius;
}

double Circle::getArea() const{
    return radius * radius * 3.14159;
}

void Circle::setRadius(double newRadius){
    radius = (newRadius >= 0) ? newRadius : 0; 
}

When I try to compile, I get these two errors:

PassObjectByReference.cpp: In function ‘int main()’: PassObjectByReference.cpp:11: error: invalid initialization of reference of type ‘const Circle&’ from expression of type ‘Circle*’ PassObjectByReference.cpp:5: error: in passing argument 1 of ‘void printCircle(const Circle&)’

I can't find the error. Any help would be greatly appreciated. Thank you!

Upvotes: 1

Views: 493

Answers (2)

paddy
paddy

Reputation: 63501

Drop the & - that's turning it into a pointer, which is not what you want. You should just write:

printCircle( myCircle );

Upvotes: 2

Garee
Garee

Reputation: 1284

int main(){
    Circle myCircle(5.0);
    printCircle(&myCircle); // You are passing a pointer.
    return 0;
}

The correct statement is:

printCircle(myCircle);

Upvotes: 8

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