i'm beginner in c++ and i get a problem

the problem is

error C2065: 'radius' : undeclared identifier

and the program

# include <iostream>
using namespace std;

class circle

    void setRadius (double r)
[B]-[/B]      radius = r;  //here the problem and i don't know why it's keep telling me " undeclared identifier "

    double getRadius()
        return radius;

    double getdiameter()
        return 2 * radius;
    double getarea()
        return 3.14 * radius * radius;
    double getcircumference()
        return 3.14 * radius * 2;


double raduis;


int main()
    circle candenter;

    candenter.setRadius (1.5);

    cout << "Please enter the radius" << candenter.getRadius() << endl;

    cout << "Circle information using function members:\n" << endl;

    cout << "Diameter is " << candenter.getdiameter() << endl;

    cout << "Circumference is " << candenter.getcircumference() << endl;

    cout << "Area is \n" << candenter.getarea() << endl;

    cout << "Circle informationusing display function:\n" << endl;


return 0;


do you know why ?

and thanks

8 Years
Discussion Span
Last Post by m18

An error like undeclared variable seems obvious to me.
Unless you are from Mars and don't understand english, this means that a variable is not declared. What I normally do in such cases is declare a variable, in your case radius.
Happy programming!!!


Oh yes, sorry. I thought minus was problem :)

Check your spelling, and learn how to read errors.


sorry , but i know what it's mean the errors

when i replace radius with m it's work
but i want to know why when i put radius it will not work

my teacher used radius and it work


Hey m18 can't you read?
DECLARE the variable radius in your Circle class.
A variable declaration is something like : int a; which declares the variable a to be an integer.
So get yer ya yas out, run like hell and DECLARE that radius variable!!!!!!!


sorry , and thanks for your help

ask for any help and i will try to help you

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