[UrIkOn]

Why I can't run 9.4-TestCircleWithDeclaration.cpp?
[Linker error] undefined reference to `Circle::Circle()'
[Linker error] undefined reference to `Circle::Circle(double)'
[Linker error] undefined reference to `Circle::getArea()'
I am using devC++.

Circle.h

class Circle
{
      public:
             double radius;
             
             Circle();
             
             Circle(double);
             
             double getArea();
};

Circle.cpp

#include "Circle.h"

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

Circle::Circle(double newRadius)
{  radius=newRadius;  }

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

9.4-TestCircleWithDeclaration.cpp

#include<iostream>
#include "Circle.h"
using namespace std;

int main()
{
    Circle circle1;
    Circle circle2(5.0);
    
    cout<<"The area of the circle of radius "
      <<circle1.radius<<" is "<<circle1.getArea()<<endl;
    cout<<"The area of the circle of radius "
      <<circle2.radius<<" is "<<circle2.getArea()<<endl;
      
    circle2.radius=100;
    cout<<"The area of the circle of radius "
      <<circle2.radius<<" is "<<circle2.getArea()<<endl;
      
    system("PAUSE");
    return 0;
}

[jimblumberg]

Have you added circle.cpp to your project? Linker errors usually mean either the function does not exist or you have not added the file with the function to your project.

Jim

[r.stiltskin]

You probably didn't add Circle.h and Circle.cpp to your project. "Add to project" requires more than just writing and saving the code.

[UrIkOn]

Oh!Thank you!
I must open a new project and add this three file into this project!
Thank You!